I'm trying to advise on the multi country seo for a site in terms of markup. We've already decided on using sub folders rather than separate sites or subdomains due to an established link profile and good rankings in all countries. The question is in relation to the homepage. Obviously this is the page most likely to rank well in any country (the site is a .com). But can multiple hreflang tags be put on the page to say that the page targets many countries? Or would leaving the hreflang tag off allow it to just rank for all countries?

Also do Yahoo and Bing follow hreflang tags? I can't find any info on this anywhere!

Thanks very much in advance for any help!