The guardian angel question is a tough one. We know they exist, and we know that children have them, because we're told the children's angels continuously behold the face of the Father. Now, I can't know for sure, but I think perhaps these children have angels before they actually come to Christ, so it could be an angel assigned to the elect even before conversion. It's impossible to know. I would not assume non-Christians have angels assigned to them, but I think it's possible.