2 pair and flush draw, facing overbet all in on turn.

I think it's well played. Sometimes he might have an overpair, but we will often be behind, I believe. I would also check/fold the turn.

We cannot call that overbet push with 4-to-a straight on the board on the turn.

Maybe it´s too weak but what do you guys think about b/f flop?
Reasons: we lead strong 4way and he raise us with a huge sizing. After his PF raise is less likely that he has an overpair (even it´s possible, some people limps everything). There are no FDs, I don´t expect he play his OESD so agro very often. Everything stronger than one pair beat us (or split). Against better hands we are almost drawing dead or have 4 outs.

As played OK fold on the turn.

Seems reasonable to b/f flop.

Yep, would make sense to bet/fold the flop, but I think it's fine to bet call two pairs and maybe check/call blanks on the turn with intention of check/folding the river unimproved.

i have no idea why he would play 98 like that

nooo such much contentedness but overall probably a good fold. If he's got the TT then our pairing outs aren't good but I also have no idea why he's play TT like that

8x is more reasonable than TT.

has to be 98 then because I don't see people raise the draw OTF multiway to be honest

It doesn't matter if it is 98 or 86 or 8x.