Opener is likely a weaker player based on stack size and limited stats though he was playing 60/30 and fairly passive in general. BB is aggressive regular squeezing 13% in this spot so likely does not have the top of his range as would definitely try to isolate the fish.

On flop easy value raise especially against this opener who is unlikely to fold any piece or draw and may get scared off on turns and rivers. The flat from the reg is a strong play though there are plenty of value hands 2pair+ that wont want to get money in this deep. When UTG makes this huge raise we are definitely well ahead of his range but it becomes slightly awkward with so much money behind. If we shove the reg can likely fold most worst hands so I call to try and get him to put more money in on the turn.

When UTG shoves as expected I think our only option is to shove as we cant really call his shove and then fold to a reshove even though it looks so strong.