"That has not and probably never will be paid."
Not sure what you mean here.
"Does wife 1 get the property?"
No, but if the property settlement agreement has the husband owing her 100% of the equity (and not just 50%), it would seem she's free to force the sale.
"If the child is still underage at time of husband's death, does the child get the property?"
You're mentioning "the child" as though you'd mentioned it previously. Again, estate debt (what's owed to ex-wife) is a priority. You'd have to clear up the equity question below.
"Does wife 2 have any claim to the property?"
Ownership claim? Perhaps, as to the husband's half-interest. First you'd have to speak to whether the equity you refer to the ex-husband owing to his ex-wife is **100%** of the equity or just her half-interest.
"What if husband leaves a will giving the house to wife 2?"
Bequests don't take priority over estate debt but, in any case, we're still not clear on what he owed to #2 (100% of equity or just her 50%?).
"Can wife 1 fight that in court no matter the age of the child due to the unpaid debt and/or the tenants in common?"
Sure, she can fight it -- can't say she'd win though.
You should consult with a local estate-probate attorney.