Bubbleponics newb needs help!

Ok so I got my SH Bubbleponics 6 plant system in a month or so ago.. I've been reading up on the system and general growing information for some time now, even years before I finally grew some balls to grow some pot, lol.. Anyway, I just recently received some nothern light seeds and 5 extra mystery seeds thanks to a lucky buy from my first seed bank purchase. I have a few questions..

1.) Does the size of the seed matter? The northern light seeds I received are quite small, yet very nice and dark like what I have read to be a good sign of a healthy seed.

2.) I am thinking of going with 4 plants, instead of 6 after reading about troubles with trying to fit 6 plants into this system with the 2 dual spectrum lights. I am growing in a normal sized sliding closet and I have a decent amount of room to work with in half of the closet with white paint on the walls. Should this be sufficient with a small fan pointing upwards from the back corner of the closet toward the plants and out of a decent sized hole/crack in the closet? any fan/exhaust tips?

3.) Is it neccesary to put black electrical tape all around the tub to prevent light from damaging the roots/seedlings? any lighting tips?

4.) I want to start by putting the seeds straight into the rockwool and then into the cups.. How many gallons of water should I have in the bucket, and how should i utilize the nutes that they gave me? nute and water tips? what kind of water?

I hope someone can help me, and maybe even send a few tips that I haven't asked questions for..

Thanks,

bongmonger

no light to roots, some strain big seed some little some both, have the water level up enough to keep the roots moist like so the water is fizzing an inch from the roots to lure the roots down

thanks for the tips HA, anyone else?