Hello Eric,
some answers:
- AFAIK the UI for M92 and M92S is the same (I have an M92). You don't need the stylus for navigating the UI, but some function won't be available, like "2 Point zoom", which I use quite a lot.
- Yes, it has standby, after a customizable delay or upon user request. (More technical details here.)
- The SDK is available and the design is based on QT. It is poorly documented as far as I can tall, but there are enough example programs to get started (and a few users ported great stuff already! Thank you guys!) A refresh API is available, but it is far from ideal, IMHO. Kernel source are available, but seem incomplete; I am tracking this down, but I have no time right now.You should be aware that there is an ongoing Android port by Onyx, but it's not here yet.
- I use usb-serial, but SSH should be usable: see the beginning of this thread for both of them.
- You should not brick the device as far as you stay away from the recovery partition
. There is a LVTTL serial console (see here), but the JTAG is still to be found, so AFAIK there is no complete recovery procedure, yet.
I'm not sure about the other answers, so I leave them for someone who knows better...

Ciao!