Yes, it's very likely that the adhesive contains asbestos. But if you want to be sure, for less than $50, you can have it tested. I'd do that anyway. Then, check w/your local township/city/whatever regarding 'regulations' on removal of vinyl flooring if asbestos is present in the glue. There may be no regulation, then again, there may be. Point is, if there is a regulation, you need to review it to see if you, as a homeowner, are 'allowed' to remove it, and safely so. If, on the other hand, there is no regulation, AND it contains asbestos, you need to see if you can get yourself up for the job.
If it has asbestos and you're allowed to remove it yourself, then you need a respirator, long sleeve everything, gloves, hammer, claw/pry/crow bar, et al.. Do NOT use any power tools or sanders because if you 'heat up' the adhesive, it will become airborne. THAT'S where the most danger lies. (You'll be OK to handle it if you dress properly.) Then comes disposal. You may need to pay a few $$$ to have it properly disposed. Contact your trash removal company or your municipality for info. The reason I don't (ultimatly) recommend you 'finish' over it, level or not, is because some day, when and if you go to sell, you MAY have to dislose its existance. And if a prospective homebuyer sees the work 'asbestos' in your house, it conjures up all kinds of thoughts on their part. It may be quite safe it you 'encapsulate' it under some new flooring but why lose a sale or 2 or 3 or more over it? You can pay now or later. Look into the possibility of doing it yourself AND have it tested anyway. (Your municipality should be able to give you a place to have it tested.)
My best to ya and hope this helps.
PS: You don't want to install ANY type of flooring over something that isn't level. Remember, the more 'sheathing' you add to a floor to make it level, you'll most likely have to cut doors to fit AND look into how much HIGHER the 2 rooms will be than the surrounding rooms. (You're gonna trip!)