[durrrr]

1) I usually would bet this turn; check is ok. Call the river (even assuming you'd never seen this guy do this line before)

2) Check the turn; possibly raise his river bet (now you know he uses this line a lot- you want added value from his bluffs; along w/ minimizing losses v trip 6s- even if it costs you value vs. AT)

3) played fine until the river. River is call > fold > big raise > ur raise. I think calling is better. You may push out AA- possibly; or you may get a call from QQ w/ your raise. I don't see any reason for doing this if you give him any somewhat logical hand range. If I'm raising this river its at least potsized.