Leash law or not, it's just much safer in my opinion to have dogs on a leash. You never know how other dogs will act, and if your dog likes leaving the yard, there is probably no way you will be able to keep him with you without leash anyway... he will want to run everywhere.
Having a fenced yard would help, but keep in mind that most dogs don't run around by themselves, so they need someone with them. But if he was used to being out a lot when younger, it would help for sure.
When did your mom decide to stop letting him come inside? It's really sad. Julie is right though, dogs that are inside all the time are much less hyper than dogs that only go inside once in a while. You could try to promise to clean after him, and vacuum every day, maybe it would help. Also definitely buy a nail clipper - if you do a search with 'nails' I'm sure you will find lots of help on how to do it.
Meanwhile, take him for long walks if you can. Leash or no leash, it's still good excercise.
Also, a bit out of topic, about your passion for Pirates of the Carribean. I liked the movie a lot too. Up to probably 18, I used to spend all my money on stuff I loved at the time - posters, magazines etc. Now I wish I hadn't, that would be lots of money I could have used on other stuff - that's including home remodelling, and dog stuff. So think about it, and try to at least save some money every month, personally I really wish I had...