Help! 400 MH, soil, 10 babies

Hello All, I'm new to the game, just found out today i'm going to be a dad to a baby girl ( there are pics, i didn't show pics of the female white hairs but i'm pretty sure), after 30 days, her stats are...
Indoors, closet
400 w MH, switchable for later, 18/6 complete darkness
Miracle gro siol, no nutes, distilled water when drying
73-82 temp 80 avg, 40-50 humidity, fan blowing around
Ph little under 7
She seems to be doing ok overall, but i do have some concerns.. #1 today the branches ( all primary and secondary) were bending ( down) pretty bad, they have bent before but today seemed to be the worse, #2 the newer fan leaves tend to be getting bluish around the edges( the first 9 finger sets are out now) , #3 and everyset of leaves new and old have a little leaf curls on the edges, curling up, and the first four leaves to come out from seedling have yellow spots, but those are really old now and never worsen or spread... I think alot of the problems are due to the soil giving it nute burn, so i never feed it any nutes.
So i found out today shes a girl now what? well first obstacle is the fact I have 9 other seedlings growing around her ( 6 of those seedlings are 6 days older then the other 3 seedlings, Pic #2 )... in my dream world i hope to have 5-6 girls growing under this one light, the light is supposed to cover a 4x4 area, can this be possible, will it have enough room? Another thing, i want to wait till the all the girls are ready to blossom to move it to the 12/12 cycle all at once, now the biggest plant will be a month older then the rest of them, is it ok to have it wait that extra month for all the others to be ready?
Now that i know its a girl i want to transplant it to a bigger pot, it has only been in this pot for about 2 weeks now but some roots are coming out the bottom of the pot, now Miracle gro sells this dirt made for blossming that contain that more need ingredent need for blossming ( begins with a "p" sorry i'm a rookie), should i transplant to that dirt now even though its gonna be a long time ( it has to wait for the other 9 seedlings to also be ready) till i put under the 12/12 cycle? Or, should I just wait to transplant to that dirt when the others show sex? Or, should I transplant it now to the bigger pot with the same dirt it is in now and feed it ( by water) what it needs for blossming when that time comes?
Other random questions... how long due i have to wait to put it under the 12/12 cycle once i see the first female white hair pistiles, or is it ready now? what node count will i most likely be at when it is time to bloosm and bud? Water is getting expensive now that i have so many new babies, i want to use tap water but i just feel scared too, can i get a bucket of tap water and leaves it out 24 hours and use that water? How can i INcrease humidity without buying some expensive machine? due more plants in a small grow area equal higher or lower humidity, and whats going to happen to the CO2 levels when the plants get larger in a close area?

Well if you read all that and your willing to replay THANK YOU very much, i will rep you also

put your big plant into flower soon, when the other plants show sex and have grown enough you can put them in afterwards, if you don't and you wait, only 1 plant will grow well, it will be so much bigger it will cut the other plants off from the light.

Do not transplant to MG ( Miracle Grow) soil of any kind, get cheap plain topsoil and some fertilizer. You already seen what MG soil does to plants.

You can leave tap water out for 24 hours, it will prolly be ok. Ideally you would use RO or distilled water.

You can usually see the pistils showing after 2 weeks of 12/12, or balls if it s a male.

The more plants you have in the grow area, the more humidity will be created, if itys really dry get a couple of pans of water and let them evaporate under the lights, they will add humidity.

CO2 levels will drop off as the plants use it to photosynthesize, if you don't have anyway of adding CO2 don't worry about it, the natural air has enough to keep the plants going. Its not optimal, but 90% of growers do not use CO2 and have good results.

You don't have a very high post count, so your +rep is worthless until you have more.

Thanks alot for the info, I really want to start the 12/12 now but i'm going to have to have it in a different room for the 12 hours dark because the others will be early in the 18/6 cycle, should i wait a little bit after i transplant to a bigger pot to do the 12/12 or just transplant asap and 12/12 asap?

proud dad to a baby girl. what the hell is wrong with you people?