To answer your fertilizer question, i don't know how concentrated earth juice is, but I use Advanced Nutrients and only go through about 45mL of nutes every 4 days or so (this is for 6 plants). So im guessing that 2 gallons will be more than enough. Distilled water has a pH of 7, which is just fine when the plants are seedlings, but you are going to want a pH quite a bit lower when you transplant and really get them on their way. Nutes generally bring the pH down lower, as will your grow mix that you mentioned. I'm not familiar with soilless mixes, but i do know that peat moss is very very acidic, so I would invest in a pH meter if I were you, to make sure your levels are in the right range. I only paid $30 for mine on EBay, it's digital and is accurate to one decimal place (ie. 6.7).

Last thing, someone mentioned T5s. I personally use a 400w MH, a 400w HPS and a 4 bulb T5. The T5 works really great, so if you were interested in how well they work, you can check out that person's T5 grow log, or you can check the last page (or maybe last 2 pages) of my log where I have posted some pics of some of my plants growing under it.

Cheers!