4x4x4 first grow, very detailed so hopefully you can help!

have a 4X4X4 grow box. I bought emergency blankets for reflective purposes and lined the bottom of the box with plastic painters mat to make cleaning eaiser. i have a 400w hps light that is cooled by a connected exhaust hose which has a 6 in duct fan inside, the hose is the lead out toward the top of the box threw a 6 in diameter whole into my crawl space. the crawl space is where i my hiding my box. since i have it locked and closed most of the day. i have the exaust hose connecting from the light running threw a hole cut leading into my attic. I have cut a 9 inch diameter hole, where i have an exahust tube that connects to the box and is also in the attic for better air supply. I have a 10 inch fan in one corner of the box. in the other corner i have a large air ionzer(hopefully filter some smell?keep the air clean?) I have 4 60wat flors attached to the walls just for an extra boost. I also have a co2 tank that ive used for paint ball and i nozzle that i can use to disstriput the co2, this is one of my questions, im not sure how to i should go about using it. i plan to use soil in 1 gallon pots and i plan to grow lowryder2 and im going to try to avoid transplanting.

So my questions are what is the maxium number of plants can i grow in these conditions at once to insure maximum yield and quality,.

also what nutrients should i use and what would the patterns be for them.

how can i use co2 tank to my advantage.

pics tomorwI

The number of plants you grow depends on the style of grow you want to do. If you have a seperate area where you can keep a few mothers and take clones, you can do a perpetual harvest SOG, and harvest 2-3 plants every two weeks, by taking a fresh batch of clones every fortnight, and moving them into flower once they take root. Using this method you would have 8-12 plants in the room at any time, in groups of 2-3 at different stages two weeks apart. That make sense?
Another option would be to have just 4 plants, veg them for a month or so and train them to fill the space with LST or SCROG.
As it's your first grow I'd suggest the latter option, purely because it's easier to concentrate on the needs of a few plants than it is a lot of them, especially if they're at different stages of growth.
Once you have a couple of grows under your belt and you start to get a feel for it, then start experimenting with changes to the setup like adding co2, and keep track of how they react to it. Plants will only benefit from co2 enrichment if all other factors are optimum, they need as much light, food and water as they can take, regulated temperature and humidity and preferably an experienced grower that can recognize and treat nutrient deficiencies quickly to make much use of it.
One thing I feel I should point out is that a 400w light is a little small for a 4x4 space. A guideline is to have 50w/sq ft, so a 400w is ideal for 8sq ft, with the side lighting you could use a 3x3 area in the middle of your space, leaving 6 inch around each side for air circulation.
As for nutrients, I'm a big fan of BioCanna, they do complete mixtures for veg and bloom in a bottle, you just have to add a few mls to a gal of water, which takes away the hassle of mixing 2, 3 or more part nutes (which can be a headfuck for new growers) I've used them since I started last year and have only seen deficiencies when I left it a bit long between feeds.
Granted, they do seem a bit expensive at £16 a bottle, but it will last, I'm not even halfway down either of mine yet in 9 months, and have grown 20-odd (good sized) plants out of it, getting between 1-4oz/plant as my techniques improve.
Sorry to have rambled on, I just wanted to answer your questions in as detailed a manner as you presented them in! ;D

ok complete post fail on my part. i forgot to mention im growing lowryders, how many low riders can i get out of that, id like to get 10 if i cant how many more lights. sorry about that

lol and sorry for making u write the explanation on the veg stage since the low ryders just skip it it but it was still usefull

Not at all, take a look at your first post, it says right at the end of the first paragraph u wanna grow lowryder 2s but I overlooked it while I was trying to answer all ur other questions lol!
Mind if I ask what made you go for the lowryders? I'd say you have the space to scrog some sweet indicas in there (I'm thinking cheese, but I just love the cheese) and yield more from 4 than from 10 lowryders. Tbh thats only speculation cos I've no info on how much a lowryder yields, but it's not going to be a great deal if they top out at 12".