Peter

I wouldn't use "boy" of grown men, so much prefer not to use "girl" of grown women, and don't like other people calling me girl. I'd prefer it if other people didn't call grown women girls either. Except possibly when referring to your own children.

Technically I will accept people referring to me as girl though: I don't call people out for it. Notably I haven't told Mike not to call me "My girl" in affection. So, I could have ticked pretty much all of the bottom half of your second question :)