3. You didn't flop a set, you flopped trips.
Your bet sizing on the turn is the problem. The pot is 1.20 and you have 3.60 behind. By only betting .60, you can't get stacks in on the river unless you overbet the pot.
Betting something like 1.00 on the turn will make the river pot 3.20 and you can bet all-in for your remaining 2.60, which will be called more than a 3.60 bet into a 2.40 pot.