Go all in first hand. If the draw calls you, you are 6-4 to win(actually better because you are better than 10% to fill up or quad). A lot of people will call an all-in with a flush draw at those stakes. Get all your money in when you know you have the edge. As for your call on the turn, he probably has it, but if both your stacks are big enough, you have 4 outs to fill up, so you can probably call if taking his stack gives enough return(you will almost definitely take his stack if you hit). Second hand, you only have 4 outs, but you will take his stack if you hit, so the turn call is fine.