To the OP--this is an awesome hand.

I have a whole bunch of questions.

In this hand, CC'ing pf (as opposed to 3betting) so we can R a favorable flop, seems useless because the pot will be too big to protect our hand regardless. When would it be correct to CC with this intention?

My first instinct on the flop was to call with the intention of raising a safe turn. Does MP3 really bet the turn with hands that we beat? If not, then we should raise the flop for value, right?

If we raise the turn, and get three bet by MP3, we fold the river UI?
If we raise the turn, MP3 and others just call, what do we do on a non spade J-8,6,4-2 if it’s checked to us?
If we just call the turn, river is as above and it’s checked to MP3 who bets, what do we do? We fold an A or K, right?