6. Is it absolutely necessary to use any nutrients? If so, which?
if your growing small, just buy the bloom nutes, let your plant vegg, then give it nutes throughout flowering, it keeps them small and saves money, the bloom nutes are most important for big buds, something high in K..

kp's cannabis college is good, but for a small grow asking specific questions usually works better, and you get more than one opinion...

good luck