> 1. Anyone selling a used one? I'll buy if the price is right...
> 2. Which games/types of games can't it play (like Star Ocean, SFA2, etc...)
There are a group of special chip games that can't be played on a backup unit. Games that use a SA1, S-DD1, SPC7110, a handful of others.
Check Fat Mikes FAQ for a list.
> 3. Can I play those games w/a bootcart?
Some games, notably DSP games can be played with an adapter.
> 4. Is there a parallel port version?
Of an SNES backup unit? Certainly, there are many: SWC DX, SWC DX2, GDSF6, GDSF7, plus many more. Super UFO has no parallel port.
> 5. If I can upgrade the RAM, what type of RAM can I upgrade with, and how much can I upgrade to? And how would I go about doing so?
Depends on what backup unit you get. Some yes, some no. Super UFO supposedly you can if you find a larger RAM board but I've never seen one for sale. Reek seems to be the only one lucky enough to have the RAM upgrade and my guess is that he wouldn't sell it.