How do you think it would be for the typical keyboard player to switch back and fourth between the two instruments
Good question. I know Paul Vandervort (who plays the the Janko keyboard, which is the same layout as the chromatone except the keys are colored black and white like a traditional diatonic keyboard) plays both the Janko and the regular piano.
here's Paul playing the Janko
and here's Paul playing a conventional keyboard
In fact, I've corresponded with Paul sked him about this, and he explained that what's going on in his head while he is playing the janko is pretty much the same as to what's going on in his head when playing a reg keyboard, except its a bit easier and he can actually look around the room more and check things out while playing.
With that said...
How do you think it would be for the typical keyboard player to switch back and fourth between the two instruments as he/she would surely have to do?
I'm not not sure he/she would "surely" have to do it. The way we are accustomed to keyboard playing is this: if you're a good keyboard player, you're expected to be able to walk up into anywhere and play their house keyboard. If you walk into a church to play organ, you might not lug your keyboard there. You might just play their house organ. Same for drums, right.
But consider that we don't treat many instruments that way. if you're a trumpet player, you bring your trumpet with you. You don't play the house trumpet. And if you walk into a house and they hand you a fuggelhorn, and they say "hey play this" you might say, the fuggelhorn is indeed similar to the trumpet, but its a slightly different instrument, and I don't play it." Even with guitar, alot of players never play any guitar but their own. They wouldn't play the house guitar. They'd go get theirs from their trunk.
So a chromatone player might choose to be just like that: "I play chromatone, not piano." And if someone asks him to play at a church or a studio or a gig or whatever, he'd say "hold up while I get my instrument from the car."
Or he could choose to double on regular piano. Whichever he (she ) prefers

What about reading music and playing this instrument?
I have not yet tried sight reading on this instrument (indeed, I am only a beginner-ish sight reader on regular piano). I plan on doing sight reading exercises on it starting next week.
Off the bat, though, my guess is that its about the same difficulty. The "pro" is that, once you are used to the major scale looking like a certain shape, all you need to do is shift your hand over to whatever the new root is, and suddenly the sharps and flats will fall into place automatically (I"m not sure if I'm explaining myself clearly right now). The "con" is that notation, as we know it in Western Culture, resolves around the diatonic scale (specifically around the key of C) so reading diatonic music in C will be easier on a conventional piano. But once you leave C, I think diatonic piano and chromatone become equally difficult.
Would a person just starting out do better with it?
Interesting question; one that I have thought of. The inventor of the instrument, Wataru Ohkawa, would definitely say students should start on a chromatone so that they learn to think chromatically, and not diatonically, from the very start. In fact, he started his daughter on it when she was about nine (I'm not sure if she played another instrument first):
And here she is about 16, playing very well (along with her dad)
In my short experience so far, I'm glad I have been playing piano seriously for the past year. I've already gotten through those difficult moments where my fingering didn't want to cooperate, or I couldn't figure out the right fingering for a riff, and those moments when I had to slow the metronome way down to 35 BPms to learn something. So it gave me some discipline that I am now applying to the chromatone.
My feeling is that without determination and disciple, you'll give up in frustration on the instrument before you start to reap the benefits. But that's not any different from any instrument, is it?
What are the notes going from the bottom row to the top row in each vertical row? Are the notes from end to end the same in each row? How many notes are in each row?
I couldn't find a map of the chromatone, but here is the map of the janko layout, which is identical except the keys are painted black and white in the way you are familiar with:

In short, vertical notes are the same note, so you have three middle C's, etc. I'll explain why that's advantageous in a future post. Horizontal, each note is a whole note up. Diagonal (up and to the right) is a semi-tone up. Like a regular piano, once you go up all the notes, a new octave begins.
A helpful tip for understanding is, in the beginning, just look at the very two bottom rows. You'll see that its just like a regular piano, but at "F", the F "jumps" up to the second row and Gb jumps down to the first row. Which makes ALL the sense in the world, once you think about it, because F is only a half-step up from E. So why should it be to the right? It should be up and to the right!
If you're just looking at the rows, how do you immediately tell which note is which?
Good question. On the japanese chromatone, it is indeed very hard to tell which note is which, as they are not painted bacl and white like on the Janko. Ohkawa did this on purpose because he clearly does not players to be thinking in terms of the C diatonic scale. he wants you to look at all 12 notes as part of one chromatic scale.
There are little tiny dots at the top of the keyboard letting you know where the C of each new octave begins.
if you think about, this is pretty much the same as guitar. Just looking at a guitar fretboard, its hard to tell which notes are which, you sorta just memorize which frets play which notes, and you are partially guided by those dots every few frets.
I myself *want* to see diatonic notes, cause I like knowing where I am on the keybord. So, tomorrow, some Avery removable stickers are arriving from Amazon that I'll be placing on the keys

How much do they cost, and are they currently readily available?
After shipping handling, and money exchange costs, I paid $907 for it. This is expensive. If Yamaha had made it, it would cost about $250 to $350 dollars. But this is a small outfit in Japan so their costs are high.
I didn't buy this on a whim by any means. I first was introduced to this instrument in 2008, and have not stopped thinking about it ever since, and made it one of my top goals this year to buy it and begin learning how to play it.
Are there many videos on the instrument?
Here's a
chromatone playlist I made