Should they be given Oyster shells? Will it hurt if I give chick grit that is of a different brand from their feed (i.e. Purina chick starter crumbles and Dumor chick grit)? Should I mix the grit in with the crumbles, or give it separately? If separately, what should I give it in? Should I/am I able to give vaccines myself or should I leave well enough alone? Should I give them any electrolytes or supplements?