Ocelaris,
What I meant by radiative is that besides the heat rising with the air currents there was quite a bit of heat felt below the lamps. I didn't see any HPS in action so I couldn't compare. I did some calculations for another thread regarding proximity of the lamps to the plants and don't believe that moveable lamps are necessary in a veg/flowering chamber. I think, as you say, we'll will start off with just the bulbs.
proximity
No CO2 for this bedroom, asphyxia can cause death. I have enough with all the dog farts to start worrying about CO2. You're right about the O2, by increasing the partial pressure of O2 in the bubbles and thereby in the atmosphere above the nutes, the amount in solution can be increased 5 fold (1atm @ ~20% --> 1 atm @ 100% O2). However, a stuck valve on the tank or power outage on the exhaust and we'll have quite the fireball. I want to smoke it, not the reverse. So, not worth the risk for a few Z's.
I've read somewhere (aquarium info I think) that with fine bubbles and at room temp up to 90% of the O2 in the air can dissolve in about 1 foot of rise. So lots of fine bubbles should easily be able to keep the solution aerated. Also, keeping the solution temp at RT will assist the solubility of O2 in water, but not much. At 20% O2 and 1 atm the solubilities are 0.000005 and 0.000004 mole O2/moleH2O at 20C and 30C, respecitively.
Also, regardless if we use air or O2, oxidation of ferrous iron to ferric rust is going to happen but it can be suppressed with the addition of EDTA and slowed by preventing the solution from getting too warm. This is one reason it's good that the nute reservoir is going to be on a concrete slab in an unheated part of the basement, it stays cool all year.
If I missed anything let me know.