Belly bands are good and maybe define him in an ex-pen with pee pads instead of giving him the run of the whole house. Don't give up on him! He's still a baby and will learn over time. Make a big deal out of it when he goes in the right places and don't punish him when he doesn't. When you see him peeing on the carpet pick him up and bring him outside.
As for your fear of pee stains: Urine is actually kind of an anitseptic! While learning about first aid for horses we were taught to disinfect an open wound with urine as a first aid in the fields.
