Villain is 15/13 AF:2 over 49 hands. What do you put him on A4? 66-TT? QQ-AA seems unlikely given no 3bet. I don't see this much aggro at 2NL without a decent hand.

Call flop and play a turn IP

There shouldn't be a lot of AA,KK,QQ,AK and AQ in his preflop range as they would generally 3-bet you in the micros although we can't fully exclude this out of their preflop range. A4, 55, 33 and 22 are in his range but as it stands assuming he is calling with a VPIP of 15% excluding AA,KK,QQ,AK and AQ you should have a 73.97% edge against his range (taken from equilab). He seems like your average nit-tag so you'd have to think what exactly he'd 3 bet you with as he just ins't 3-bet bluffing you often. 55,33,22 and A4 all seem very likely here given how deep you guys are playing. I actually like your fold here as many players just aren't advanced enough to 3-bet bluff or 3-bet semi bluff you at 2NL

Given all these assumptions it is still is a very tough spot to be in as his range could be fairly wide even though he is NIT-TAG but cold calling from the small blind generally indicate's to me that they have a bit wider range than 15%.

I agree with this. No point inflating if you could be second best.

There are several cards which may make Villain slow down (any club, the board pairing if they have a straight) and thus give you an opportunity for a cheap showdown.

The fact that you hold the Jc is bad though because there are a few semi-bluff combos that they can't have in their range any more (AcJc, KcJc, QcJc, JcTc) making it slightly less likely that they are bluffing.

I don't like playing this way (I'm not saying it is wrong and it may be a leak, I would appreciate advice). If I call his donk and he leads out on the turn for half to a full pot bet what do I do? Raising a donk is a very aggressive move in the micros, most people fold, for him to come over the top is a move I've rarely seen. I imagine I will face this sort of thing more if I move up but I feel the raise gave me a lot of information. I don't mind him folding on the flop as there are a lot of turn cards that scare me A-Q, any club, any 4 hence the raise.

As played i'm folding flop. It's kind of that situation where you're getting 3-1 on a call but you're pretty much behind every time. Unless you're playing with a complete ******, in that case i'm looking to get it in anyway.

I don't know why you'd raise that into a donk bet though, your value range is very strong against his but just call it off as he's already bet bot and see a turn. How you play from there is up to you

This above. I don't think he has you beat, and you can't play fearing the set on every flop that was raised.

The odds are he has overcards or some pocket pair and is freaking out. Why?

1.) There is a flush draw. Bets pot to push you out of draw odds.
2.) He has a mid-range pocket pair, and will fold if he sees an overcard. He's betting as his hand will only get weaker.
3.) He doesn't have an Ace, but pegs you for one. So either a 4 or A. Again, he pushes you away from drawing odds.

AA, KK, QQ, or AK? Doubt it, as I would like to think that someone with 15/13 would re-raise you pre-flop with those premium hands.

Ultimately... I would commit or give up sooner. Either play JJ softer, or more aggressive. If you stay in it, you are most likely in a toss-up situation, with either a big win or big loss ahead, and overall have a small margin one way or the other. If you play softer, you won't lose as much. This would be "selecting which hands you want" and picking which pots for how large.

i like the fold, i dont like the reraise on the flop, if he is giving value to a draw like 45c it's good just to call and play some turns, if he had you beat with QQ (rarely) you lose the min so still good call, if he has 2 pairs you can play some bad turns to him, i dont know what are you trying to accomplish reraising a nit with that board. if it was to get a fold and fold if find more ressistance (vs loose players its ok to me), but if it was that the fold was fine.