Re: How to get the Prost & Sakura dog tags...

Currently the unlock requirements for both dogtags are unknown, similarly they haven't been distributed yet it would seem. Though it's safe to guess the Sakura tag is for Japanese players and the Prost! is for German players, though some had guessed it was related to Gamescom. Similarly it's uncertain if you need to log in from the respective countries or play a few games from the respective countries. Until DICE elaborate on the requirements and also distribute the tags we have no way of knowing.

As for the second question, use of VPNs so to speak isn't condoned and should be used at your own risk.