You didn't mention what material the frame is made of but I assume steel.
Frame Saver is all you need for the inside of the tubes but it doesn't do any good on the outside.
Anodizing is for aluminum - I don't understand why the shop would suggest it for steel.
Phosphate coatings are a good idea but not strictly necessary. It leaves a coating on the metal which protects it while the frame is awaiting paint. It also provides a small amount of additional protection and gives the paint something to bite into to.
What kind of paint is the shop going to use? I think this is where you should focus your energy, not on the undertreatments. Powder coat is the most durable finish, although a two part urethane top coat on top of some sort of two part epoxy primer is perfectly acceptable as well. I'd avoid using single stage paints such as acrylic enamels since these won't be as durable.
Hope this helps and good luck.