Overpair on a paired flop (noob post)

I'm fairly new to FL (I mostly play NL), so here's my thinking for the whole hand...

CO has vpip 11% (over only 32 hands, but at least it rules out him being a super loose/passive typical fish type)

Villain has vpip/pfr 20.4/1.4 over 147 hands. I dont think he bets the flop as much as he should, but I think he's a winning player.

Texas Hold'em $0.25-$0.50

Hero [ K [img]/images/graemlins/club.gif[/img],K [img]/images/graemlins/heart.gif[/img] ]

ANTES/BLINDS
SB posts blind ($0.15), BB posts blind ($0.25).

PRE-FLOP
2 folds, Villain calls $0.25, 1 fold, Hero bets $0.50, CO calls $0.50, 2 folds, BB calls $0.25, Villain calls $0.25.

FLOP (8SB)[board cards 9 [img]/images/graemlins/diamond.gif[/img],2 [img]/images/graemlins/club.gif[/img],9 [img]/images/graemlins/spade.gif[/img] ]
BB checks, Villain checks, Hero checks, CO checks.

I check because the only hands that draw out on me are an Ace or smaller pocket pair. Hopefully I will induce a bluff or at least convince them im bluffing when i bet the turn (if they don't). What hands are realistically going to call a bet on this flop (and those that do are surely more likely to fold the turn UI?).

TURN (4BB) [board cards 9 [img]/images/graemlins/diamond.gif[/img],2 [img]/images/graemlins/club.gif[/img],9 [img]/images/graemlins/spade.gif[/img],4 [img]/images/graemlins/diamond.gif[/img] ]
BB checks, Villain bets $0.50, Hero calls $0.50, 2 folds.

I thought I had to look for overcalls (at the time) because only hands that beat me will stay in for two bets cold (and if the BB has 2 pair, for example, then he has only 2 outs and is not getting odds to call). Villain is likely to be bluffing and I thought I would make more money from him by letting him bluff the river than by raising here. There are few straight draws I let in, but Im now thinking maybe I should have raised this to cut out flush draws.

RIVER (6BB) [board cards 9 [img]/images/graemlins/diamond.gif[/img],2 [img]/images/graemlins/club.gif[/img],9 [img]/images/graemlins/spade.gif[/img],4 [img]/images/graemlins/diamond.gif[/img],6 [img]/images/graemlins/spade.gif[/img] ]
Villain bets $0.50, Hero?
I think I'm ahead of villains range of legitimate hands, so I'm thinking I should raise this (even though he probably folds any bluff) and grudgingly call a 3-bet?

Any comments on any streets appreciated.