3 misplayed 1-2NL hands

[ThinkQuick]

First time playing 1-2 NL, cashed out +$152 but definitely could have done better. Hoping you guys could help me with my lines on a couple of my hands.
My folding was good, my stealing/bluffing attempts were good, preflop could probably use a bit of discipline, but hitting a hand gave me a little trouble:

1) AKs in MP
1 EP caller, I raise to $8, 1 LP caller, Button calls, BB calls, EP calls
Flop K J 4 with 2 diamonds. ($41)
BB checks, EP checks, I bet $15, LP folds, Button folds, BB calls, EP calls
Turn [K J 4] 2 (no diamond) ($86)
BB checks, EP checks, I bet $30, BB folds, EP calls (Ep has $10 remaining after this call)
River [K J 4] A [img]/images/graemlins/diamond.gif[/img] ($144)
EP throws in his remaining $10, I call.
I am obviously not throwing this hand away, but it sucks that this river completed both obvious draws. Can I prevent him from getting there?

2) JJ in EP
folded to me, I raise to $10 (it is later in the game and this is a more common PFR), one LP caller, BB calls.
Flop Q 7 2 ($31)
BB checks, (LP looks ready to muck his cards) I bet $25, both fold. Is this bet size wrong for my purposes?

3) J7s in BB

6 other players in and I flop a flush, with OESFD (5h 6h 8h)
What are the principles for betting here? I want someone to at least chase the straight, but I was nervous of letting the Q [img]/images/graemlins/heart.gif[/img] in to chase thinking it was good if another heart hit., Anyways I bet $15 into the $14 pot and took it down on the flop.


edit: added pot sizes to the first 2 hands.. I guess I can see what happened on the first one.