How old is this rooster?

This rooster is on our property. We live in a more rural part of town where it is not uncommon for people to abandon roosters. But he is so beautiful, seems well cared for, and is very VERY loving. Asks to be picked up in the morning. Follows us around the yard.

How old do you think he is?

Should we keep him? Would we need to get chickens? He thinks our kids are his flock. Would he still be this sweet if he has a flock of girls?