I nwonder if this cat may have cerebellar hypoplasia. It is a congenital defect from the virus of panleucopenia which the mother cat has somewhere in the last trimester of pregnancy or when it is just a week or so old. That accounts for the strange balance or weakness. It may have chronic sinusitis causing the snuffling snoring wheezing sounds and the vomiting may be due to hair balls. Many cats vomit a couple of times a week and live fine with it. There is also a condition called inflammatory bowel disease that can cause vomiting which is a chronic condition. If the cat is maintaining his weight OK I wouldn't worry. It might be a good idea to give Cat Lax or Laxatone or Petromalt a couple of times a week to see if that helps. Intermittent antibiotic episodes help control the upper respiratory sounds but you won't cure any of these things.