I don't have any info on the rest of your questions (interested myself, actually), but I can answer the s9 differential.

The escape is the bottom end unit.
The elite adds smartstart, mask fit test, and data logging.

I was looking at several a few weeks ago on various area craigslist locations -- but they seem to have dried up everywhere! Any other suggestions where a guy could go to pickup a non-outrageous S9 AutoSet? I travel a fair amount for work so I'm looking for one to leave prepped and packed while using...