Villain is 25/18/3 over 100 hands. Should I be 4-betting here preflop?

How about the flop? Is calling here OK OOP?

On the turn, villain thought for a long time before checking behind (not playing on any of my other tables) This made me really think he had the flush when the river card came... AA/KK just calls here right.

PokerStars No-Limit Hold'em, $0.50 BB (5 handed) Poker-Stars Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver Cards)

Button ($9.95)
Hero ($83.80)
BB ($85.95)
UTG ($129.80)
MP ($39.65)

Preflop: Hero is SB with , .
3 folds, Hero raises to $2, BB raises to $6, Hero calls $4.

Flop: ($12) , , (2 players)
Hero checks, BB bets $7, Hero calls $7.

Turn: ($26) (2 players)
Hero checks, BB checks.

River: ($26) (2 players)
Hero bets $18, BB raises to $40, Hero.....

Final Pot: $62