Anybody w experience w grapefruit or snow white!

I just ordered some grapefruit and snow white femenized, is there anything special that you would like to advise me. Like are they stable, low or high stress, harvesting time, best yield, and how they are with potency, and ppms on nutes. Gonna use gh flora series with big bud and overdrive. How long a flowering. Would greatly appreciate it. Also, should I top plants or leave em natural. I'm trying to flower 8 plants in 4x4 tent w 2 400 watt hps.