Re indoor vs outdoor. I have had cats that lived a very long healthy life outdoors. it is more natural, but if your cat is a male he'll probably get in cat fights .We waited too late to have a male neutered and he got in fights all the time. currently we have cats that live indoors and i let them out for a couple hours each day. they have gotten to look forward to this and love it. they will roll in the dirt and eat grass and just play. As far as fleas, treat your yard with diatomaceous earth and it will cut down on that. You can use it on the carpet too. We give our cats flea baths and all that.
also our city has an ordinance that says cats have to be on a leash like a dog. Most of us cat owners think that is really dumb but it is the law. Technically they can fine you if your cat is out and not on a leash even if it's laying in your yard. The dog owners in our city insisted cats are to be treated the same as dogs.
Our cats live better that a lot of humans.