how are his middos? How was he as a roommate in Yeshiva? Is he a considerate bachur? Does he help out at shabbos meals? How is he with kids? for a girl the exact same thing. except if she didnt go to seminary, then you dont ask that question but you can ask, if she is involved in any sort of chessed projects. does/did she help take care of little sibling if applicable.
Please do NOT ask what size clothing her mother wears or if they use plastic table clothes on shabbos! or if they are stackers and if they use real dishes etc etc.