100nl- c/r set called with flush turn

I have stats on the villain; however, I'm wondering what is going to be the best play in this situation against an unknown.

Is the flop c/r a bit too small? What's our turn line here for the flush coming in, and for a blank? Thanks.

$0.5/$1 No Limit Holdem
6 players
Converted at weaktight.com

Stacks:
UTG ssnon ($346.80)
UTG+1 lessharm ($151.35)
CO omahondo ($123.10)
BTN MrDunns ($104.90)
SB mixen82 ($60.85)
BB Hero ($140.75)

Pre-flop: ($1.50, 6 players) Hero is BB :7c: :7d:
3 folds, MrDunns raises to $4, 1 fold, Hero calls $3

Flop: :3d: :qd: :7s: ($8.50, 2 players)
Hero checks, MrDunns bets $6, Hero raises to $18, MrDunns calls $12

Turn: :ad: ($44.50, 2 players)
Hero ($118.75)?

Played a hand almost exactly the same as this just now, though the turn card that brought the flush was low. Raising the flop to $18 is fine imo, anything within the range of $18-22 is good. I bet $28-32 on the turn, with the intentin of calling a shove most of the time. If he just calls i shove any non diamond river. In the hand I played villain shoved turn with aa with no draw to the 4 flush.

Would a check be at all appropriate on the turn to allow him to rep the flush?

I kind of want to take a bit of time and bet like just over half pot but I really don't know if that's good. I figure if we have to think about it and bet a rather smallish bet a few hands with a diamond would stay in that might not want to bluff turn or call a big bet as the Ad seems to be a pretty good action killer. I'd c/r flop bigger though because I think most hands that call a c/r on the flop are calling a tad bit bigger sized raises.

Id bet here. He'll have a hard time folding any pair + diamond, like KdQ or QJd or something like that. Might even have KKd or two pair AQ here. b/call it off.

How much are you betting, griff? I like a $28 but could be really bad.

I don't mind a bet of around 30.

I think on this board, hands that will peel with pairs + FD's are probably just as likely to call $34ish as 28ish, so a bigger bet might not hurt.