How long does this game take?

We have only played it once so far, and it took about 20 minutes.... but that was with a couple 7 year olds (and the television was on in the other room, which in our house is always a factor). I'd estimate about 15 minutes on average, maybe more.

How durable are the penguins, do they warp easily if squezzed or oinched, they look to have little slits on the sides above the wings do these weaken (turn white the way some plastic piece do when stressed.) I like that the game seems to be very simple and based onsomething kids like to do anyway (stak stuff) I'm just concerned my kids might push them down really hard, squezze them or otherwise mal treat them in an innocent exuberence that youngsters tend to exhibit.

I don't think you need to worry on that count. They're pretty durable little penguins.