Most if not all tuners encrypt their software while on customer's cars, but afaik they keep the OEM software in their DB.
1. absolutely no, REVO maps + encryption still there
2. the REVO dealer can upload the OEM software in the car
3. exactly as Hedge said + new owner might have a "check engine" on because (at least in the MK5 GTI) the IC has a checksum that is compared to the ECU checksum. If they are diffrent "check engine" pops up.
Mate, try to get in touch with the REVO guy, for him it's a 15 minute job.