In the upcoming state tournament, I know that the top seeds actively play the Tarrasch against the QG. I want to have ways to play against it. 

I right now know that the bishop fianchetto on g2 is strong to target the weak IQP, but I have recently lost a game due to a small trap. The Tarrasch is a bit hard to deal with. 

The tarrasch is playable by GMs so theres no easy answer. Study a few games  and plans by white and practice them here in 15 min games, review and refine.

If you don't like the positions with Bg2, you don't have to play them.  They are the most promising for White according to most strong players for the last hundred years or so, but it is more important to play positions you feel  comfortable and confident playing than in choosing the "correct" line according to current fashion.

Either 6 Bg5 or 6 e3 is perfectly playable, and both lead to positions rather different from 6 g3, so your opponent may not be very familiar with them.  Try them out in practice games and see how you like them - choose the one that suits you best.