We have a total of 7 cats. (all are fixed, we rescued a momma cat, and had babies, and then my daughter talked her dad into keeping ALL the kittens, except 1, she gave one to her best friend... then she found another kitten and rescued THAT one from a parking lot. It had been separated from it's mom who was a feral and the kitten trusted her enough to let her grab it.)
She convinced her dad, to keep that one too. After I got all of the cats fixed, the 4 barn cats live outside, my old man cats live inside (They are both in double digits and haven't spent a day outside in their life with out supervision), with the feral kitten she rescued. I hand raised the litter, so they are friendly and don't run away, but the feral kitten I never trusted to go outside, I was worried she wouldn't come back and my daughter would have been heartbroken.
If I asked for a cat, my husband would say no, but my daughter bats her pretty eyelashes at him and she gets whatever her heart desires. (which is how we ended up with chickens, and a pony.)
I think my outdoor cats, do a pretty good job of mousing outside. I always see them carrying stuff around.
As to kids... we lock up our sharp knives. and anything flammable. Or toxic. If we all survive teenager-hood... maybe i'll take that trip to harry potter world someday.