scrubbing will only help to remove a majority of the die off, which may help to speed the cycle(vs. leaving it on, but only some), but if you have any sponge or anything, i would definitely remove stuff like that, you can get pretty aggressive with it if youu want(it is rock), it does not matter alot how much debris you keep, you will still have plenty to start your cycle withbut i would rinse with saltwater, using fw will also kill some of hte stuff that you wnat alive
as far as the lights go, off is better for curing and cycling, it will help ot promote coraline grwoth
HTH