FML river spot with set

3betting preflop would be a definite adjustment, and you should usually be flatting. I would prefer to have a better read than that one note before I adjusted. However, given the exact content of the note I would be at least a little tempted to 3bet (although I think it would still be 'wrong').

Flop check back is whatever... I would usually bet half pot or so, but it is no big deal if you want to maintain a polarised cbetting range here.

River is obviously a completely horrible spot. In practice I always call here... but I always get shown AQ. When I am playing my absolute A-game then I make the fold... and of course that's the one time in a thousand that my opponent is bluffing!