does that freezer still have the insulation in it. if so that may be an issue with the heat. 50 to 60% humidity would be ideal. dont let them get above 80 for verry long at all, not good. i would recomend 18/6 right away, nature dosen`t have 24 hour light, they need thier rest and seem to grow faster overnight. i used to do that and bring my hours down to 12/12 gradual ( didn`t want to stress them) but all your doing is delaying harvest, i dont feel there was any benefit in yield or health. also figure out your cubic feet in freezer then get a higher cfm fan and if you have a filter on it you need a bit more because of back pressure.