So I've been wondering something.

Wizards and witches are longer lived than Muggles. How much longer?

Do witches have the same amount of child bearing years as Muggles do? Would wizards and witches wait til longer (say 40s-50s) to have children, when that would be considered rather old for Muggle parents?

Why don't more wizards and witches have lots of kids like the Weasleys? Most other pure-blood families seem to have between one and three kids, while the Weasleys are just outrageous in comparison.

Would wizards and witches look younger than Muggles of the same age (at say, middle-age, 40s and 50s)? Or do wizards and witches just have a longer time being old?