20/40 Kill, oop w/ 3way action

[npknhldr]

Live game, players involved are all TAGish, observant and thinking players. BB is LAGish, good player.
Seat 1: Hero SB w/ 99.
Kill in Seat 6. Folds to post, kill post checks, CO raises 80, I call.
BB calls, poster calls. 4 way to flop for 320.
Flop: Kd9s4d.
SB bets. BB calls. Poster folds, CO raises. I call, BB calls. (Pot $560)
Turn 6s.
SB bets 80.
BB calls 80.
CO raises 160.
SB calls, BB calls.
Pot (1040).
River, 6c.
I bet, BB folds, CO calls. Pot: (1200).

Issues: #1: Hand range for CO. #2: Turn action.
There might be more to this hand then meets the eye. Though I still think my line wasn't optimal, it may be closer than I thought.

Issue #1. Though CO opening range is wide, based on how play unfolded the range I put him on is (AA[x6], KK[x3], AsKs[x1]) So, I'm ahead here 7:3, but factor in 44 and AKo (though based on player history AKoff would not play it this strong on turn, 44 unlikely due to kill pot) and weird ass bluff raises and anyway, lets round up and say I'm 5:2, or 71% ahead, 29% behind his range. BB looks like he has a draw, though I wasn't thinking of combo draws at the time or AK, 44 etc. AKo more likely for BB than CO, imo.

Issue #2: Reasoning for turn: Should I have 3bet? prob. Why? How much more do I win? How does the equity change heads up?

To be honest, I was looking to extract absolute max money here, and (stupidly) was willing to risk the pot to the draw. I think as played when I'm winning I end up making the same amount of Big bets (5) as I would've if I had 3bet turn and if draw folded.
But if draw called turn I would've made 6BBs, possibly 7 if I get called down (by AA)? Also there was a chance I could make several BB on river on some cards (c/r, b/3bet) if played incorrectly by opponents (9d, Ks, 6d?), especially if I only call the turn (they still should think AK is big part of my range here, I think i gave off good fake tells and played it slowy/tricky). Remember I'm looking to squeeze the draw and the vulnerable made hand (presumably).

Also, If I 3bet turn, chance that both players (incorretly) fold, and I only make 3BB, but with zero risk. But, that would've pissed me off...

Constant factor as well is losing the min. # of BB when I'm behind and extracting the max. equity when I'm ahead. Positioning is key throughout the hand I think.

Comments on other streets welcome (PF, flop). I like my flop call turn lead line oop, though maybe I'm misguided in this thinking.

CO had: <font color="white"> AsKs </font>