re: Poker & limit goodness
Pre-flop, hand range is huge to call a 3-bet from SB, but not that huge. AJs and up, TT and up and maybe KQ suited: not a lot of people are in the hand and he knows he will have to play OOP.
On the flop he called your cap and at these limits, I rarely see a capped flop unless someone has two pairs, trips, an overpair, a made hand (QJ or AA) or a combo draw. Him donking the turn and calling your raise indicates a great deal of strength, so I don't think KQ is likely here. Only hand I'd be worried is QJ, but him not 3 betting the turn with the absolute nuts indicates he doesn't have it.
As was played, the only hand that makes sense is two pairs, AA or TT and maybe AQ (but even AQ would 3 bet the turn). Raise river, we're ahead way more than 55% of the time here and aren't likely to get repopped while very likely to get called (villain has sown a willigness to go to showdown in this pot pretty much 100% of the time by betting river).