Well, no help on all the questions but neutering at 18 months vs 2 years wont make much difference, Cutty was neutered just after he turned 1 for same reasons actually (dominance and bad attitude) and he filled in great I think. Also the neutering did fix his attitude problem I would say 95% almost instantly. If you are having problems there are of course MANY things you can do to work on it but neutering does help. Back then I had no knowledge as to the training and how to work with him so I didnt try the other things on him first. This site has taught me a LOT! As for the couches and pee I have no idea. My pups run the couches and they are a mess. lol I would think ammonia would be a good cleaner as well tho for carpet and pee but no idea on how much per water etc.