I'd betting that flop as I don't expect any pocket pair to fold along with Kx which we beat. When they overbet on the river, I'm not sure this is a call as I never expect to see KQ or worse here, but it's certainly not a raise.

This is a super easy bet/bet/bet spot. As played I think raising over the overbet is an overplay even if your hand is somewhat underplayed (due to the flop check). I'd just call.

Standard spot for three streets of value. Slowplaying is generally to induce some bluffs into any villain's range but people aren't going to be so forthcoming in a five way pot. If anybody has the case king then they're unlikely to fold it if you just bet bet bet at these stakes.

There's also no difference in value between c betting and getting two streets from a decent pocket pair or checking the flop and getting it on the turn and river. What is different is that you've limited yourself to only two streets if somebody decides to trap with a worse K but won't ever raise it.

As played I would only call the river once he overbets.

Just fell off my chair. Please don't slowplay 5-way with the effective nuts. Easy flop bet, going for several streets of value. This hand was a huge waste of value.