how to play the on turn with a hit set on the flop

Call pre is fine, 3-bet is possible, personally I 3-bet JJ+ as a standard. If UTG is opening too loose, I would 3-bet this pre.

Flop, why would your opponent raise (or check-raise) you when they flop a flush? From his perspective it's better to just call with a flush. He doesn't want to slow your possible bluffs down. He can just check/call twice and jam river. Maybe if he has some weaker flushes he wants to check-raise turn. I don't see why you would think he should raise the flop with a flush.

As played, I can get behind the large size on the flop. It's multiway, both villains can have single spade hands that have great equity against you. You want to make them pay to see a turn. On the turn though, I don't think you have to go pot-size. You want to go large though, like 2/3th-pot, something like 22BB is fine in my opinion.

On the river we can shove all-in or check back. I think most of the time a check back is fine here. He shouldn't have that many 8x type of hands, so I'm not concerned about the straight so much although his single spade hands missed the flush and will fold anyway. What hands on the river call your shove that we beat? Then again, he can have some flushes that hope you bet the river again.

His correct line would be check/call, check/call, lead river all-in. But it doesn't really surprise me when they take a more passive line on NL2, since the player pool is generally more passive. Doesn't mean they never have the flush, it just means they don't know how to put in enough aggression correctly.

Long story short, I think you played it fine.

as played, I don't like any of it, sorry. preflop I would 3 bet. you have a lot of small stacked behind and you want to put some pressure on them. On the flop i am 1/3 pot betting, any multi way pot you want to be more cautious. As a rule I use whenever a villain bets in a multi-way pot i 3x there bet size. example if they bet 3BB then it is really a 9BB bet, this helps because things can get out of control pretty fast in multi-way pots. As for your bet sizing on flop- all a big bet does here is blot the pot, at this moment you have a bluff catcher with a set of tens, you are drawing to a boat but it isn't made yet. Any flush or high card draw is most likely calling unless you go all in. Now on the turn I would be willing again to bet small especially if checked to. As when your first bet is called and not raised on flop, villain can have a flush already or Ace club or King club. Unless you are willing to overbet pot anyone with that Ace or king is probably coming along to the river, and once again you are blotting up a pot where you still only have a bluff catcher. As for river checking is GOOD, if villain donks into you. i would fold. Main thing to remember multi way is to play more cautiously..