Utg(110bb)-aggro when chk to, will fire 3 barrels
Utg1(covers table)-playing his cards only. 30's
Btn(100bb)-old nit
Me in bb (120bb)-viewed as aggro, I've been ISO raising a lot in pos because I have position on a whale

Utg limp. Utg1 raise to 12, btn call. Bb calls out of turn so I call with A5cc
Flop T62ccc chk around. Should I lead here? I figured the Pfr would cbet any OP with a club.
Turn 6 I bet 20, bb raise to 45 and I call. Riv Q I chk, he bets 60. Hero?

Played terribly on every street. What position are you in? There can't be two People who are in BB???? Lead flop. This is a terribly flop for PFR. He might miss flop or he may pot control overpairs. Lead flop to get value, not get it checked through, so you can get stack in by river, and so you can get players sandwiched in the middle in case PFR raises flop (which is not too likely unless he has KxKc or QxQc since you have the Nut FD blocker).

When you flop monsters (unless you flop nut boat or better in which case you check) in multiway pots, esp when draw heavy, leading flop is almost always best.
Bet bigger on turn (2/3 pot or so). Reraise turn. As played assuming Q is not a club, shove river. Do some hand reading. Only hands that really beat you are TT, 22 and Q6s, T6s. There are way more 6x and smaller flushes in his range. You aren't even that deep

Bet the flop.
Call the turn.
Call the river.

lead flop man.

another thing to think about why leading is better is if the 4th flush card comes on turn after you check it through whats calling your bet then? probably only K or Q and even those cards could find a fold a lot to big bets. Also those hands will call leads on flop to hit their draw.