Q1. That husband is a genius. Makes her happy and avoids the drama.
Q2. "How can I politely steer myself away from these questions?"
Stop worrying about polite.
"A: Wow, you know a lot of dreadful people. I, too, had a baby at 40 (the regular way, not that anybody asked me) and I can't recall one person saying anything but how happy they were for me."
This. If I had something negative to say about the situation, I'd do the right thing and say it behind their back.:)
Q3. I think these peeps are being unreasonable. I mean why is it such a big problm to let mom invite some of her friends, especially if she's willing to pay. I paid for our wedding. No money from the parents. I certainly did not have an unlimited budget. But I was more than happy to invite a few of my mom's friends. Friends that I did not know at all. It made her happy to have her friends there.
Q.4 "A: If I understand, the question you're asking me is if you should pursue a romantic relationship with your male ex who is becoming a female ex."
WTF?!? You need to ask?
Q5."he wraps his left arm protectively around his food and hovers his upper body over it"
He eaither has a bunch of older brothers or spent time in prison.
His behavior is not going to magically change by itself. If you want him to change, you need to use your words.
Q6. "A: It's very sad to have to estrange yourself from your family, but that may be your only recourse."
Q7."Do I owe her the truth as I understand it?" Yes.
Q8."Should I forget the age difference and enjoy the relationship?" You want Prudy's permission? You're to stupid to date.