Another thing, if there are tomcats, I would get a female, that is spayed. That way they should get along.
Kittens should never be left alone outside at night.
And if you get a cat, make sure to keep it locked in the house for 1 week, so it knows who you are and everything. Then you can let...
I would go to a local shelter and see if they have any cats that were brought in as strays. They will be better than kittens for catching mice and moles.