Hand#1: Bet the flop, there is a good chance yo uare ahead, and you have overs+draw. On the river it is really read dependant, he could have played a flush, or even trips the same way.

Hand#2: Your main reason was raising too little preflop, you want to thin the field to 1, possibly 2 players, and you are not going to do that with a minraise, espcially not when there are 2 BB posted.
With 4 people seeing the flop someone must have hit something. On the flop you should either raise or fold (proably raise) and on the turn you have to fold to the push, if he pushes when 4 people call he has a good hand