A. I'd never marry a person with children under the age of 30.
B. The empty nester would depend on how empty their nest was. If their kids had grown into productive adults who can care for themselves and were either child free, or lived at least 4 hours or more away, and I really REALLY loved the person, I would consider marrying them if I were in that position. Certainly, they would have to respect that I would not accept children, or adult children, living in our home for more than a week.
"It truly is the one commonality that every designation of humans you can think of has, there's at least one asshole."
--Me