Apple cider vinegar is a very acidic alcohol.
So drinking it can actually make you drunk, and the acid in it mixing with your stomach isn't that good for you.
It has health benefits, but i don't think its good to consume it.
Maybe. Studies have shown that vinegar helps metabolize fat in mice, but no double blind studies have ever been done on humans. It doesn't really matter when you take it -- the easiest thing is to make your own vinegar-based salad dressing.
Don't overdo it on the vinegar. It can eat away the enamel on your teeth.