6500k would be good to get now as you probably won't be vegging for very long and they are not really needed for flowering. (Some say they help, and I don't disagree but with CFLs your often working with so many primary spectrum bulbs as it is that adding many more is just to big of a pain)
As for the soil, sadly I cannot really give a suggestion on whats a good brand from stores like Lowes as I'm yet to find one myself. Miracle grow Organic, and Miracle grow moisture control are probably my two favorites though as with a bit of perlite they seem atleast to me to not clump as bad as some of the others.
Moisture wise, water is of course the lifeline of plants, but at the same time they also need air which you starve them off when you have to much water in the soil. Generally I prefer to do a strong watering and then wait a few days till the soil is pretty nice and dry and then rewater them, hard to say exactly what to look for though as its kind of something you just get a feel for as you grow. (Stick your finger in the soil about 2-3 inches to tell how moist it actually is as the lights will dry the surface)
Transplanting wise I would probably try to do it sometime in the 7-12 day range from actually sprouting. That should give them time to grow enough in strength to handle the transplant and also enough time afterwards to do any recovering/adjusting they need to do before you kick them into flowering.
As for lights, when I did CFLs I always just went to lowes on payday and I would get me another pack of whatever spectrum I was needing, until I eventually had about 450watts of actual CFL wattage which suited my space, but price wise Amazon usually has good deals. May also want to consider buying some t12 fixtures from lowes (9.99$ around here but I forget bulb prices) and putting one or two in the corners of the closet for nice addition side lighting as that many plants in a space like that will get pretty crowded.
Mind telling us what type of sealant your using? Always helpful to learn new ideas