I would add one more question to the list -

How well do you know yourself - can you house a kitty as a foster and give him / her up when the time comes?

I had 6 cats and was quite happy with that. I decided to foster. Ebony is cat number 7, and I took my name OFF the foster list half an hour after she entered my home.

I think the cats would be happier, and easier to rehome if they are adjusted to indoor life. But you have to consider the cats you already have, too.