Hand 1: This is a fine spot to double barrel. Just double barrel for $21-22 instead of $15.

Hand 2: Here i would try to keep the pot smaller. If villain fires at the turn we can reevaluate, since 8-8 is ahead of a reasonable amount of an aggressive opponents double barrelling range. And if he checks we acquire the pot a higher % of the time.

Hand 4: definitely call AI preflop.

Hand 6: is close but i prefer a fold in a spot like this. Even when i am confident an opponent has a big pair i want at least 12:1 IO to call with a smaller pair PF. A good player could avoid stacking off with K-K/A-A in a 3bet pot on a really nasty flop, though almost never for only 70BB's. Still you are only getting 10:1 and there is no guarantee villain is holding K-K/A-A.