1. It's cheaper because you. don't have to import all the way from USA. Asian units comes directly from local distributors.

2. Unless either of you or your friend have bad internet connection you should have no problem with online multiplayer.

3. Asian 3DS are basically the same as NA 3DS with different labeling and adapter. It won't affect online multiplayer compatibility whatsoever. I don't remember any region lock for online MP other than Fire Emblem Fates.

1200+ for a 3DS!? How many stuffs are you going to get along with the handheld itself? Or is it a special edition 3DS you're getting?