[Harv72b]

With that structure you should be completing with any two suited cards pretty much every time. If the game is loose (as I presume it is), you can expand that to any two connecting cards as well, with the possible exception of the lower range like 32o, 53o, etc.

I'm not sure where you're getting your numbers (50/50 when you make your flush? 11 cards that beat you on the river?), but you absolutely need to be calling on the flop. I'm hesitant to make a value raise on the flop, given that the board is paired & it appears that more than half the field acts after you do; however, if your opponents have been apt to call multiple flop bets with weak hands/draws, a raise is probably better.

If you ever consider not betting that turn, slap yourself repeatedly.

Assuming that your opponents in general (and the SB in particular) are the kind of loose, straightforward players which typically populate these B&M stakes, yes the river is a call. Given the strength of your hand, the lack of action on prior streets, and the size of the pot, the only other action you should be considering would be a river raise.