Neg double is fine.It only promises one 4 cards major(not 44)after opp's two over one overcall or weak jump overcall.You can check this from Mike Lawance's book.
Always 1m. When you have a powerless hand,rebid 2m,or rebid 1M if you are lucky.If you are strong enough,you can make a reverse bid. Do not worry of missing a major fit .If so,it must be a part contract.