How'd I play these hands?

I was playing a 40$ sitngo at a home game yesterday, 8 players and a ridiculously fast blind structure. With four of us left I had ~4000 chips, two other guys had ~6000 and the short stack had ~1500. The blinds were 100/200.

First hand I'm wondering about I was the small blind and the short stack was the big blind, I raised to 500 with k/8 offsuit and he went allin, so the pot was 2000 and it was 1000 to me so I called. Good call?

So he had k/10 and I lost that pot, I doubled back up, and a
couple hands later the blinds were now 200/400. Again it was down to the same two players in the blinds, this time we both had around 4000. I decided to go allin with k/9 offsuit, was this a good play? He called with q/j suited and knocked me out. If it matters, top two paid, and the other two guys had around 4500 I suppose. I actually thought the other two guys had more chips but I guess they didnt. I just finished reading Harringtons second book and he really preached aggressive play with low M's so I thought I should go allin with a decent hand in k/9, but maybe I could have waited a few hands I don't know.

[cha59]

The first hand: I think you either want to push all in preflop or fold here. You only have 10x the big blind. Make your opponent make the tough decision instead of facing the possibility of you having to decide whether or not to call his all in. I don't know if I call his reraise or not, I guess it depends on my read of him as much as anything at this point. I try to avoid situations like this.

The second hand probably is fine.

Yes the payout structure is relevant to your question. It looks like you need to get some more chips to get in the money, so you have to gamble some.