Veneers are a great cosmetic option (mine are 25 years old) but when teeth are missing and there are cavities, after looking at new x-rays and an exam, you would most likely need a combination of crowns and veneers. Depending on how large the cavities are, you may require the treatment of a few root canals in order for the tooth to support a crown. Once a tooth has had a root canal, it requires a post (which is like a rebar when cement is being poured) then the core has to be built up, then a metal free crown. Without the pictures and xrays, its hard to really say what you would need. The first step is to come in for a consultation. I have done hundreds, if not thousands of veneers and makeovers as I lived on the west coast. Whatever you do, do not rush this treatment, it has to be done right!