We own a hardwood flooring company, and we try as much as possible to avoid this kind of job. It may be a nightmare. Really all depends on the adhesive used. You may want to consider asking a professional to have a look. There are tools, and chemical adhesive removers once you get the tile up. You are correct, if it is very old at all you are dealing with a hazardous material. Be careful of your exposure and how you dispose of the materials. Contact some local commercial flooring supply companies, and also some of the major hardwood flooring trade associations. There are flooring contractors who specialize in restoration work. Be really sure the wood floor is worth saving before you invest too much time or money!