Yes, I'd say that most of that is inappropriate and represents some instinctive biases. On the plus side, most of your examples demonstrate someone who is at least willing to think about these things, but yes, they're micro aggressions.
Re the crappy unsupportive husbands, I'm afraid I don't think that's homophobic or even sexist. Statistically, men are more likely to be abusive partners and/or useless (all those stats about household chores sharing, for example). Doesn't mean all men, nor does it mean no women are, but it is true that overall, this is true.
To answer this: So I guess my question is, straight mums - are there any aspects of hanging out with a gay mum that you’d find a bit different or unrelatable? Gay mums, did you get othered at all?
My only potential concern regarding any kind of social activity with gay mums might be if I developed a friendship with one, and then inevitably we got into a bit of a "girls" evening out type event and the one I was friends with always brought her wife along. And even then, I think this would only really be an issue if 1. I didn't like the wife and/or b) they were all very coupled up on nights out. I like couple events - don't care if they're gay or straight - but I personally really value time with female friends, without our partners, too.
We have one quite close male gay couple friends - DH and one of the couple met through work years before either of them met me/friend's DH. And we all get on well. They don't live close these days but when they did, and when we do see them, we all get on well as a couple group, we've attended lots of bigger group events and parties over the years etc. But sometimes Dh and his friend will still meet up for a drink or a catch up, or perhaps with other friends of theirs from the "old days" and neither me or friend's DH would dream of attending.
The questions about male role models I would find really offensive. Do they ask single mums if they are going to actively look for male role models?