Two hands I think I misplayed in AC Taj Mahal 50+15 multi

[Marc Desjardins]

A little before the first break, we started with 5k in chips, I have about 12k, blinds are 200-400 with ante of 75. I'm maybe in first or second position in chips at my table. A player who just sat at the table is UTG+1 or UTG+2, he says raise and then says he needs to decide how much. One player in middle position says something I didn't hear and the guy says "why not, I go all-in" and he goes all-in with about 4-5k in chips. It's folded to my one off the button and I see AK offsuit. I thought for a while, the guy was smiling, didn't seem to stressed out. I put him on a high pocket pair or at worst AK, but I didn't believe in AQ or AJ. So at best I felt it was a coin flip. So I folded.

Now at the Taj, the blinds go up very fast after the break, but I wasn't familiar with the structure, it was my first ever live tournament, so I didn't want to gamble. Good or bad?

Second hand came at the 8th level, there's about 75 players left out of 244. I have about 16k in chips which is close to average. I'm close to chip leader at my table. The blinds are 800-1600 with 200 in ante. I'm middle position, the player the my left has about 3k left, so I figure I need a hand that I'm willing to get to the river with since I can't get him out if he goes all-in. For the last few hands, I've been telling myself that if I get something worth raising, I should probably go all-in.

It's folded to me and I find A5 suited but I couldn't pull the trigger, I raised to 5k. The player to my left went all-in for 3k and the player to his left called my raise. The small stack just said he was bored and wanted to go play the slots, so he could have had anything, but he didn't matter. The other player was moved to our tables a few hands ago, I had no read on him. I think he had close to the same amount of chips as I had. The rest folded.

The flop came K82 or something very similar with 2 clubs (my suit was diamond). I checked, the other player moved all-in and I folded...

So, 3 questions:

1-first hand, do you call the all-in at that point with the AK?

2-second hand, what do you do with the A5 suited, open limp, open raise (if so how much?), move all-in?

3-second hand, what do you do after the flop, check, bet (if so how much?), go all-in?

Thanks in advance...