Specific questions:
1. Can they run one wire between the satellite dish and the junction box?
No, You will have many cables from the dish, the number will depend on the config/setup.
2. Is this better inside our outside?
doesn't matter. inside, always looks better
3. I have called at least one dealer who told me that I don't have to wire all of the boxed to a phone line, but I don't know if that is true?
mini1 answered this...
4. I was looking to maybe get four boxes - two with Tivo if possible.
Any advice on which service to get? It seems that one service may have a limit of four sets and Tivo dual-tuners count as two.
This setup should be possible with the correct multiswitch.