c/c. You don't have that many ax here so you are basically raising jx for value and spades. Also that check is really suspicious that should be a 100% bet. I would rather raise a betbet here with T8s. That check just feels so trappy.
I think pre and flop are both standard, x/c is standard on turn as well, you're getting something like 22% pot odds to draw to your flush here, a backdoor flush at that, so your hand looks quite disguised when you do hit.
When you brick out the river, I just don't think there are many credible value hands you can rep here. So just x/f.
3/4 pot is generally fine as a turn probe spot in pretty much every situation you're turn probing. In theory you can sometimes pot, sometimes not--but you run into issues like exposing yourself to error by potting it on this board where the added size folds out very few added hands and just pays the turned Ax off even harder. Bigger turn probe sizes also expose your draws to value shoves more.