when he overpots the flop you should raise a lot more, he either has a hand he likes an he is not folding or a NFD that he will call. so as a c/r i would go to 0.7$
when he calls flop and turn makes a flush you're pretty much beat cause FD are the most of his flop calling range, another set, 2pairs would go all-in on you.
on this board an vs this loose/passive opps as you say,turn i like c/f , c/c , b/f better then b/c because there is not much worse he can call when we bet and we always get raised by better . his raising range has us crushed in general on this line , while we have better equity vs his betting range when he bets if we check.
as played fold river always