Problem with laying new vinyl over old is any thin spot will show. Vinyl by its nature needs a 100% smooth and solid surface. The embossing leveler might work OK, but I'd sure have a flooring installation company look at the job and get their advice. Taking up the old vinyl, asbestos or not, is a B***h of a job for a DIYer. The pros have machines to "git er done". With your health situtation, I would suggest hiring it done and while they were doing the job, take a vacation to a nice motel, have some dandilion wine and rabbit stew, then go home to a nice new floor.