I think the hand is played fine until the river. I don't play HU too often so please excuse me if the questions are "stupid".

Villain will have some busted spade draws that he will bluff if I check. Does he shove AJ or even worse against a check?

Given the fact that I cbet the flop I am a little bit more likely to have spades than hearts (especially because there are less combinations of me having good made hands containing hearts with the Kh on board). I might turn an AAxxSS into a bluff on that river or maybe a hand like KQJ*. Is there any chance he would fold a straight if I am not a super nit? How thin do people bet this turn for value? I guess any straight but I am not sure about Sets/Twopairs ...

Does the 99 in our hand change the way we play the hand? It reduces the combinations for straights and therefor shifts his range to nut straights and air more.

Thank you for your comments!