I think that your hand is too weak to open from UTG and doesn't play great in a 3bet pot with 100bb stack vs a 5% range. I would open fold and fold to the 3bet.
As played, I like flop, if we fold top pair we can simply fold preflop. Turn sounds good to pot control, vs a range so strong. River is a fold just if villain is never bluffing, btw this is the kind of spot where their value range is wider than their bluffing range.

Next answer please.

I think it's a marginal call of the 3 bet and I agree that if we open utg this isn't a hand that's going to play well out of position unless we flop the fd or the flop comes all low. I would fold flop because if he has hearts, a wrap or an A high broadway run down we're not doing too well - a set of As is also a possibility although I guess we have a blocker
ps I posted this before I had my coffee and didn't realise how high the stakes are.....i have no business commenting here

I don't usually open this hand UTG(my stake is ZPLO100) though this depends on population tendency. I actually think that this is open at lower stakes, but fold at higher stakes(I have not played at PLO500 ps)...want to hear what you think about this.

Note that we are in position vs BB, that makes a call vs 3bet from BB.
I think we should fold on this flop though vs 5% 3betting range. As you said, it is gonna be very hard to realize our equity and we have no heart so that we can bluff 0 turn. Even if he doesn't have a Ax, he will have plenty of equity vs our hand.

A lot of talk about your UTG open. I think it's fine IF the villains are too tight, we can profitable steal. Although I would choose a hand with more playability like a 10-8-5-6 ds hand to steal as we can hit weird hands and profit a lot because flops that hit this range won't hit a typical UTG range. If they fold, our steal has been successful.

Once the BB 3B us, we should be folding pre-flop. The BB 3B vs an UTG open is too strong, unless our UTG vpip is wide and he knows it. Now on the flop, we can't fold. We have to call now because of the back door nut flush, and top pair with some back door straight to save us just in case. On the turn, he checks, now on the river, when he bets. We have called the flop. We could have AAxx ourselves and slow play it because he 3B us and then check the turn for obvious reasons.

When he bets into us on the river, he's rarely bluffing as this is a horrible place to bluff. The draws missed and he checked when the straight came (90% of his straights would bet normally). Because this board hits our UTG range and he bets into us. He should know so many draws missed and that this board hits our range, we will be calling down decently light and therefore a bluff here is terrible. When he bets, I consider this a very easy fold.

Obligatory comment about this being is way above my stakes. I fold pre twice. post flop seems correct to me. Flop we are in position with good back doors, it seems like way too strong of a hand to be folding even though we don't have great equity against his range. I like the turn check back a lot, I think having this hand in our river range after checking really strengthens it in so many ways. This seems about as good a hand as any to be calling otr. Preflop just seems really bad to me though.

Is it too nitty to just fold the flop? Considering that his range slams this board and our utg range should also be strong enough to continue most of the time so he shouldn't be cbetting very light.

Pre is whatever, I think it's a bit loose but fine. I can't see how we can fold to BB's 3bet though, this is a mandatory call.

Flop is a fold. How do we "roughly" calculate it? Well, against his $3b4o range we only have 36% equity, and even less if he actually has a checking range. And like you correctly assumed, we can't really realise our equity on future streets. If you think about it, your UTG open/call 3b range should have a plenty of stronger hands than this one, so folding this is fine/standard.

Turn is okay, this is one of the best cards on the deck for us but I see no good reason to bet (we are still behind his range, so we can't put a value bet and protection bet won't work often enough).

River is a must fold, calling here is just way too loose.

Pre-flop seems fine but flop is definitely a fold. He has you crushed way to often and I think the time he has 4567ds and your ahead he just check folds because from his perspective the board hits your range pretty well too.