Hi,
Fold on the Kc, it could have hit his weak-c-bet range. Some guys have the balls to bluffshove that scarecard at nl25 but you won't run into them that often. So unless you're specifically planning to call him down with a read that he'll bluff those cards always, you're better off putting the money in on the flop if you're not gonna give him credit for JJ+ when he bets the turn.
2c not so different in the end. He's less likely to bluff that card because he can't expect you to fold whatever you called the flop with, but his range hasn't improved this time. I expect most people to just shut down there without an overpair and you only beat one of those, it's not worth the call down against an unknown.
I totally agree that these folds look weak against good aggro players, but few of those are playing nl25. You'll save yourself a lot of money by giving more credit to the players rather than by calling down lighter. All of this is of course assuming that this guy is some sort of tag, if he's a total donk or an aggro monkey by all means call him down.
Hope it helps.