Flat pre seems fine because if he's flatting alot in position his 3bet range will likely be pretty polarized and to get more value out of that air portion of his range just calling preflop is best. I dislike your flop lead, all it does it put you in a confusing spot on the turn and he's (probably?) going to c-bet almost all of his air on this flop so leading sort of stops him from doing so.