Hand 1 with JJ i would have 3bet preflop to try and narrow it down to a hu situation and it would probably give me a better clue as to what villian is holding. I do like your 3bet on the flop but you imo if you were gonna 3 bet there you should have just shoved because no matter what came on the turn you were gonna put it in the middle. Oh and you forgot to add pocket 3's and 4's and even Q's. Also as dumb as this sounds 5-6s and even 3-4s (SB) its 2nl man you gotta be ready for any and everything.

Hand 2 i would have raised to hopefully take the power of the button and if UTG reraised i would have instantly folded. I never limp anymore i'm raising or im folding. As far as the rest of the hand goes i would have done the same thing you did most likely but i would have put in a valuebet on the river. I would have made it low probably like 30 or 40 cents just in case he has top pair and missed the gutshot straight or he had Q-10 and missed his straight but still has tp. or he missed the flush draw and wont call anyway. I mean if he raises then i wouldnt stack off but i would call his raise up to around the pot because it could be a bluff.

Hand 3 i would have fired another pot sized bullet. If he wants to keep calling for the flush so be it and i'm repping trip queens and it appears i am unafraid of the K by firing another bullet.

Hand 4 i would have C-bet and repped a overpair. I wonder what he smoothed called you with?!?!

Anyways i hope my anwsers helped give you insight in some way. tc