Hello faronel,
Preflop: You ain't really ahead of many hands with just 9x therefore rather 3bet with the hand vs SB steal.
As played
Postflop: Depends a lot on the villain although I wouldn't assume that he is folding his Kx hand, which might even be for me Check behind rather than Betting. He may sometimes even float with Ax hands there and we just value-town ourselves.
Best Regards.