"I don't feel that a cat should be kept a prisoner in the house"

Pet owners tend to project their own feelings into those of their pets. There is no reason to consider a cat being a "prisoner" in the house. If you had bird would you feel the same? Even a dog? The world of the cat has been adapted as they were domesticated and there are enough challenges and stimulation inside the average home to keep the animal happy. Because you or I might feel prisoners, there is no reason to assume the animal feels the same way.

I think it would be cruel to suddenly stop a cat from going outdoors once it is used to doing so. You can't change behavior. If the cat were trained as an indoor cat from birth, you will have no problems.

Our cats have not been declawed. Even modern practices remove part of their toes from what I have been shown. We have scratching posts and there have been no problems with furniture. Again, it is how they are trained - and you can train behavior in cats.