Unless using the higher-wattage CFL's (or HID's)...worrying about reflected light is unnecessary. The light isn't strong enough to rebound off the walls, head back to the plant, and be a benefit. (usable light from a 26w CFL is about 6 inches, max) Still not sure I understand the need for a CFL hood, but they seem to sell. Perhaps they're just for the really high wattage CFL's. Using the proper bulb for the growth cycle is helpful too.

I'd ditch the foil and leave the box as it is. Panda films and the like are an unnecessary and expensive extra. Tears, scratches, noise. I'd add a couple more lights soon and if heat becomes an issue, add more air circulation and ventilation, and a larger box or closet will be necessary soon.

Now is the time to start asking about nutrients and micronutrients you'll need, the best soils and soil ammendments to use...

And of course there's the ph pen or test kit as mentioned in a previous response...