This is a typical hand that always troubles me

Villain was pretty active, however I didn't have a lot of reads on him since it was early in session. He often limped in earlier position and then would usually call if the pot was raised behind him. I usually put people on a mid to low pocket pair, however he was doing this often so he couldnt have pairs every time.
A round before I had the same hole cards and made a c-bet on flop and he folded. This time he didn't. His river bet.....bluff or not?

PokerStars No-Limit Hold'em, $0.02 BB (7 handed) - Poker-Stars Converter Tool from FlopTurnRiver.com

BB ($1.21)
UTG ($2.10)
MP1 ($4.59)
Villain (MP2) ($1.43)
Hero (CO) ($3.05)
Button ($0.81)
SB ($1.23)

Preflop: Hero is CO with J, A
2 folds, Villain calls $0.02, Hero raises to $0.08, 3 folds, Villain calls $0.06

Flop: ($0.19) 7, K, 7 (2 players)
Villain checks, Hero bets $0.15, Villain calls $0.15

Turn: ($0.49) 2 (2 players)
Villain checks, Hero checks

River: ($0.49) 5 (2 players)
Villain bets $0.32, Hero folds

Total pot: $0.49 | Rake: $0

I was so close to calling just to see what he had. I wouldn't doubt if he had bottom pair or something similar. I can't think that he wanted me to call with the size of the bet. Should I have bet the turn?

You could call. If he sees a lot of flops, it depends on how aggressive he is on the flop. I have stats on a regular at 50NL that are 60/0 with 0 flop aggression over 1k hands, which means he never bets. If this guy bets, I'm folding 2 pair.
You have to figure out if he is just loose passive, or if he is capable of bluffing.
Bottom line: I wouldn't bother, unless you've have seen him bluff the river before.

Also: make it 10c to go preflop.

With no further reads on what his aggression means this is a pretty standard fold. Pretty much never a bluff.

Oskar is correct to point out that you could raise more preflop. While 4bb + 1bb per limper suggests $0.10 there's really no reason to just automatically do that here. We can easily bet $0.10 and be called by worse, because your read on this player is that he limp-calls anything. If you bet to $0.20 pre-flop this villain would probably still see a flop with a wider and weaker range than a strong players cold calling range. I'm not saying bet $0.20 - I'm saying understand why (in this situation in particular) there is profit to be found in betting bigger with the limper in the pot preflop and decide yourself what the appropriate adjustment is.

People limp-calling are often calling stations post flop also, so barring any read otherwise I wouldn't bluff. I wouldn't second barrel and I might not even cbet. In this case I'd probably still cbet because a paired board just hits less hands overall.

(Basic observation: If there is no pair on board there are 9 cards that would pair the board that can be in hand ranges. With a pair on board there are 5 cards that could either pair or trip the board that can be in hand ranges. This directly translates into fewer hands hitting a paired board - making it a good bluffing board.)

The board is pretty dry, so I'd be happy to cbet smaller. If this is a fit-or-fold kind of guy I might even go below $0.10, but $0.12 is certainly not unreasonable.

Fold here. You don't have near enough equity with high card to be calling a bluff.

You played it fine. Now fold.

Start asking questions like "How often does he bluff" instead of "Bluff or not". Sure he is bluffing here sometimes, but given the price you´d need to be good like 30% the time or so.