I found an amazing article for keeping mothers. It's a great read for any experience level. http://forum.grasscity.com/advanced-growing-techniques/291687-bonsai-mums-guide.html
You will need a lightproof area inside of your room to seperate mothers/clones (18-6; 20-4; 24) from your flowering area (12-12) Any light inside the 12-12 light cycles dark period for flowering will harm production and possibly cause the plant to turn hermi.
5ft squared is the general rule for 1000 watts. You can top the plant at any point. The stress will shock the plant causing it to stop growing until it recovers. Most top very early
Also, metal halide isn't the best for flowering. You need high pressure sodium (hps) Look into conversion bulbs. I don't know much about them. To do this right, you will really need to open your wallet. First decide what method you want. Then you can set up accordingly and pick genetics. You...
Start here: http://boards.cannabis.com/indoor-growing/132514-noobs-guide-growroom-set-up-work-progress.html http://forum.grasscity.com/absolute-beginners/446508-ideal-conditions-grow-marijuana-list.html
As far as reflective coating goes, check out roof-gard 700. It is an elastomeric roof...
The problem with matching exhaust and intake is positive pressure. Pulling through a hose, filter, or lights decreases exhaust. If intake > exhaust, the filter can't do it's job because air is pushed out through cracks. Smells escaping is bad for business.
Respiration rates of plants are sensitive to temperature changes. Plants take in carbon dioxide during photosynthesis in the day, and release it during respiration at night. But they don't necessarily photosynthesize and respire at the same rates. Eventually half of the CO2 they use in...
The purpose of co2 enrichment/ac is to eleminate exhaust/intake and to increase production. Your lights should be on their own isolated system unless your ac can handle the heat output. In that case, open hoods are fine. The room should be as close to 100% sealed as possible for co2 efficiency.