From my understanding (could be wrong) the system is at factory settings so the only thing it might read different is the air coming from the intake if we have a MAF sensor. I wouldn't think it will "relearn" any exhaust stuff, i doubt we have a sensor their.
Yep. It would have to be re-mapped... as far as I know no one has cracked the U.S. ECU yet. That is why I say any mods to intake or exhaust will be minimal until someone breaks into the ECU and offers mapping mods.