Hand 1: Yes I think you missed a value bet on the river.
A check on the river could be ok to induce a bluff from a missed draw though, but you've showen too much on the earlier streets I think for that to be likely. If you checked the turn that play would be more likely.
As played, about 20-25 could get a call from a Q or T.

Hand 2: Villain underbets the pot twice, which doesn't really say anything though. He could have the K, trying to trap you, or he has nothing. Looking at the river action, he probably has the K or the nut flush.
On the turn you have the flush and SF draw, I could find a reraise there.
I'd shove the river too. When you go for the flush, go for it when it hits. If he has the A of KJ, cry.