I would not make so many diet changes if not necessary. Feed what the breeder is feeding, decide what diet you ultimatesly want to have him on, then start the transition process after he's been home for a few weeks. I would not plan any middle steps unless he rejects the final diet plan.So I should definately switch to raw dried then? then try moist food then actually go to raw.
I think it was certain strains of worms is what I heard it helps with but if I went organic and grass fed to begin with I wouldn't see that being an issue.
If you are going to be feeding raw you should deworm prophylactically at least twice a year.