1. Do those of you with adult children still use childlike terms to describe or address them? "Boy/girl," "little," etc.?
No and yes. My sons are in their 20's. I address them as my sons and speak of them that way in conversations with people outside of the family. Yes, between my sibs and me we still might occasionally refer to our children as "the kids" in conversations with each other. But none of us use that term when speaking directly to our sons. (none of us has daughters). I guess it is more a term we use talking to each other that helps us feel younger than we all are. (50+)

Oh, and every one of them is taller than us - so "little" wouldn't apply!
2. Do any of you have parents who address or describe you that way? How do you feel about that?
Our parents do not address us in that way. And if they are talking to others, they will say that they
had 5 children. Beyond that, they will refer to us as adults and talk about our accomplishments in life.
I have had experiences at work where a manager might refer to some of us as "girls". That definitely raises my ire! If they were age 75+, I might let it ride - it was a typical term and not meant to be demeaning of that generation. But anyone else -
excuse me, but I might be old enough to be your mother. Do not call me a girl!
I'm thinking that your mother might not actually mean to sound disrespectful with the way she addresses you. It might just be her way of apologizing - she can't say the words you want to hear - but she can allude to them by calling you her darling little daughter.
Just thoughts...