a. How is it intonated?

Basically, by changing the position of the tines towards pickups the tone can vary from Wurlitzer-like to a muffled deep tone, and from soft to loud and distorted. The trick is to get the whole keyboard balanced, providing a solid bass, transparant low mids that sound saturated when played hard, high mids with enough body and lots of twang when needed, and nice sustaining high notes that sound fat.

The tricks to achieve this are numerous and can only be learned through experimentation, good ears, and one to one comparison between different Fenders. Well, and good taste and lots of listening to good music of course!!

Furthermore the action has to feel even over the whole range. To get both sound and touch right and thus create an instrument that is reliable requires skill.

The Fender Rhodes materials and construction of keyboard action have changed continuously during the years. But even Fenders with similar serial numbers that are customized the same way can sound differently depending on how much a piano has been played during the years and due to small construction differences. Fenders that where build from 1978 generally play light, earlier Fenders usually are modified.

Look at it this way: to get the most out of a Fender takes a lot of time. In the factory a Rhodes was put together but that is about it. It was simply to costly to invest the time needed to convert it in the instrument that had the reliability and sound you hear on records. A Fender that has not been properly intonated, technically upgraded and customized will always sound much wimpier than a Fender that is beefed up. It usually does not react to your playing like you want it to and often there are so many little things that irritate that you can't even play it properly at all. Keep this in mind when you buy one secondhand and convince the seller that you have to invest extra money to make it sound good.

Was it a pianotuner who intonates 3 Fenders per year and never took the time to really dig into Fenders and experiment? He will probably try to convince you by telling he does everything according to factory-settings. Unfortunately the endresult will not be up to standard. It needs more expertise. That is why I am a fulltime Rhodes-technician.

On most tracks Fenders are recorded "direct to tape". If it is a fat, direct sounding Rhodes without effects there still will be equalizing involved. By using the preamp of the Suitcase-model, or a good external parametric equalizer (connected directly to the harp-output to have more high-boost or more control over the midrange to stand out in a crowded mix). A parametric quality EQ with "High Z" instrument-input and 4 broad bands is handy when recording Stagemodels.

Electric guitars that are DI-ed usually sound characterless. A Rhodes can fully display its character without the need of an amp modifying or creating the tone. However, tube-amps introduce overdrive and subtle distortion and extra harmonics and the possibilty to record a "Fender sounding in a Room". With effectpedals the Rhodessound can be changed beyond recognition or subtly broadened. The Suitcase-model has a solid state amp build in. It sounds not very bright and it's not used much.

No, due to different mechanical constructions of various Fenders different approaches are possible. Also, for instance, if a customer is a rough bluesplayer who wants the roughest sound possible and wants to play hard and heavy and does not really care about the best dynamic control, I will approach the Rhodes differently from someone who wants the easiest dynamic/timbre responsiveness, immediate reaction from the keyboard when playing soft, and still have fat high notes for jazz-soloing.
Also, when modifying the keyboard for faster action, different approaches yield different results, ranging from "very light" to "piano-touch".

Well, it looks great. However the Suitcase speakerbox is not that special. It simply does not sound bright and does not bring the character of the sound upfront. Also, the solid-state amplifier is electronically unreliable and repairs are costly.
The only interesting thing about a Suitcase is its pre-amplifier. It functions as a DI-box, equalizer and stereo-pingponger. But it is also often defunct in some way and the only really interesting type is the one with the round knobs, not the one with sliders. The slider-type pre-amp sounds a bit muddier.
Try a good parametric 4 band EQ with broad bands and high-impedance (High-Z) input. It will save you money on future repairs, can sound just as good and you do not need to carry the box around. Take your time to find ideal settings. You will not have the original pingpong effect however, and that has a rhythm of its own.
The reason that the Suitcase is still often used live is that it looks cool and by turning the treble and bassboost knobs you get an acceptable sound instantly (if the Rhodes is properly intonated). The sound-engineer does not have to worry about equalizing, and feeds the preamp stereo-output directly into the desk.

Well, here is another myth used by sample-manufacturers. Let's talk about tuning an acoustic piano first.
You will probably know that a tone consists of a root note with a series of partials (overtones) superposed on it. The combination of various loudnesses of overtones creates the timbre of a tone. In a piano these loudnesses of partials of a string are amplified and filtered by the soundboard, trying to create the best possible airwave tittilating your eardrums.
The frequencies of the partials are determined by simple mathematical order, imposed by the Divine Dude himself. But that's not the whole story, because this clear and simple Divine Order gets obscured by various physical side effects. So, the partials of a pianostring usually sound a little bit higher than they theoretically should, due to stiffness and little frictions and tensions at the end of a string. The shorter the strings are, the bigger the deviation, that is why you always see those large grands in the concerthall.
Now, suppose you want to tune a A1760 Hz to a A 880 Hz that is in tune. The procedure for these higher octaves of the piano is to tune the A 1760 Hz beatless to the first overtone of the A 880 Hz. However, the first overtone of an A 880 Hz (1 octave higher = 1760 Hz), sounds a little bit higher than the theoretically expected value, let's say 1762 herz. That means that the rootnote of your A 1760 Hz ends up at 1762 Hz to be beatless with the A 880 Hz one octave below it. The octave is now STRETCHED. So, all piano's are stretchtuned, the amount of stretching depending on the length of strings, not so much on your pianotuner! So can you stretchtune a Rhodes? Well, not in the sense I described above, which is the proper one. The reason being that the overtones of a Rhodes-tine are much closer to the theoretically expected values than a pianostring, just like the tuning-fork you might own. That's why the highest notes of a Rhodes always seem to sound a bit low, although perfectly in tune with the notes below. Maybe because we are so used to the pianosound and for psycho-acoustic reasons.
I usually only tune the very last notes of the Rhodes a bit too high, so I get a small beat in the last octaves that is acceptable, thus trying to compensate for Mr. Harold Rhodes "Too Divine Design". But that is not stretchtuning, you cannot strechtune a Rhodes.
The lower notes of a Rhodes are very much influenced by magnetic pull of the pickups. Their frequency depends very much on how hard you strike them, but this can be effectively used to enhance the sound and give it more character.
Even experienced pianotuners can not properly tune a Rhodes, it requires a Rhodes-tech who can tune acoustic piano's; a guy like me :-)

They serve two purposes. They improve sustain and they can be used to tune those hard to tune high notes instead of using the little springs on the tine (or using both).
Sometimes they can diminish sustain, but just leave them on the tonebars or store them in a jar so you do not lose them; they are very hard to get.

Yes, but air-humidity also has something to do with that.........which brings me to the next subject:

a. ALWAYS store it in a dry environment. It prevents the tines and pickups from corroding and consequently turning your instrument into a unreliable, worthless museumpiece.

b. Place it in its natural playing position to prevent structural shiftings and bending of screws that hold your Rhodes together.

Twin Reverb: Blackfaces sound better than Silverfaces but are hard to get. The problem is the relatively small cabinet. It can not really digest the lowest basses of a Rhodes and the equalizing is limited. But I personally like the combination of a Suitcase-preamp and a Twin. It also has very pronounced high frequencies. It can produce extra drive and harmonics.

Bass-amplifiers: A lot of people like them for a Rhodes. The Rhodes does not produce a lot of overtones over 8000Hz, and usually the EQ of a bassamplifier is in the right range. The box can handle the basses. Try one with elaborate graphic EQ to control the midrange color of the Rhodes.

Roland Jazz Chorus: Not my favourite, to clean and I do not really like that chorus-dipsauce.

Keyboard-amps: They have a linear frequency response. A customer of mine uses a Peavy on stage and it sounds pretty good. Usually these amps are solid-state.

Tube-Lesliebox (type 145/147/122/251): Sly Stone used one on his "High on You" record. Alotta tube character present here!! But it has a very limited high-frequency response, so you will need to boost the highs.

If you like effects try them all, especially before you buy.

Phasing: some classics are the Mutron Bi-Phase (hard to get, expensive, some vintage unreliability, but very impressive), the Small Stone-family by Electro Harmonix (3 brands available, the older the better or try the reissue) and recently Bob Moog gave us the Moogerfooger MF 103 with sweepable 'hot' frequency for very accurate and musical phasing effects.

Chorus: I personally like the TC electronics "vintage" footpedal.

Wah Wah: try until you find one in the appropriate frequency range, or sweep EQ.

Ringmodulation: try the monstrous Moogerfooger MF 102 for early seventies Miles Davis/Headhunters jungle/space-fx.

Overdrive: use a tube-amp or convert your Rhodes into a guitar with guitarpedals.