Uses for juicer pulp
This depends on the type of juicer and how well it extracts the juice from the fruit. The best juicers leave a relatively flavourless pulp (which is, however, very high in fiber). If you're curious about the flavour, try tasting it! (I've heard of the pulp being used to make muffins, but other flavouring agents are definitely required).

I am not sure about the vitamins, I am willing to guess that they exist primarily suspended within liquid (water for the water-soluble vitamins, oil for the fat-soluble ones) and a good juicer will leave only trace amounts of either type in the pulp.