Open this always if a 71/57 player is behind me, only 7 hands ofcourse but opening 55 from utg in zoom is pretty standard imo unless what you say there are tough players behind you.

Flop I would cb. Call when he raises. I think its an easy fold on the turn. Its a bad card for villain to bluff on, we dont have any stats or something on him so I would just let it go.

I play lower stakes, so I could be quite far from the right path, but anyway:

1) Having a loose player PF (and perhaps CS postflop?) on our direct left is not a good reason for not opening this kind of hand?
2) Why calling the raise OTF when/if we are giving up on a lot of unimproved turn? Which turns are we going to bluff? 
Are we planning on bluff on any diamond, or only some of them, like if the K of diamonds comes OTT.

@Sue The reason opening 55 with a 71vpip player would be good is because if you flop a set you will likely win 3streets vs weak holdings. If he was an aggressive 3b'r opening it becomes less attractive.

 OTF: We are folding too easily if we just bet/fold flop. We likely have ten outs vs his value range and are ahead of his bluffs so getting almost 3/1 on a call we should not be folding. I was not planning on bluffing any cards tbh, I was just hoping to suck out/check down enough times for flop call to be ok.

A 7-handed sample is not worth much. I don't recall opening that many hands in my first 7 hands of a session, so the only read you can get is that he probably has a wide range.
And him flatting the HJ vs your UTG open sort of supports that, since there aren't a ton few hands you should be flatting there.

Because of this presumed wide range, you should bet for value and protection.
Definitely not folding on the flop. Even a loose player doesn't have two pair except for maybe 43s on this board, so you're looking at a couple of sets, flush draws, Ahighs, overpairs, and random bluffs.

The 4 pairing makes it less likely he was holding 44. He will likely bet all of his flush draws (and BDFDs), and continue on his bluffs.
Folding this street in a vacuum would definitely be a mistake, imo. The problem is that all of his overs, FD still have good equity versus your hand.

I would call the turn and evaluate on the river.
A small consideration is that most aggressive recreational players tend to go crazy on the flop and turn, but shut down on river, because they think they won't get a hand that called twice to fold.
If the board bricks, it's actually pretty dry, so it's not like you'll be folding much either.

I think you are giving some 1 tabler whos played 7 hands waaaaay to much credit for deep thought processes. I think the turn is an easy fold. We are OOP, we dont really have any good idea what his tendancies are, so have no idea how to play the river and even if we are ahead, hes got decent equity vs us.