Go with as much light as you can produce: the shop lights are really the way to go. (2) 40 watt bulbs is good, but 4 are even better, esp. if you don't use staging to raise the plants to within 6 inches of the bulbs. Forget the charcoal, it's not needed and Pyro's comments are on the mark regarding its use. I used inverted pots to raise the level, masking them with live sphagnum moss. There are problems in using pots in a natural setting: it is difficult to provide tray watering. You might want to consider some form of individual resavoir for each pot/species which would let you place pots in esthetic spots rather than be limited to one level. Do be careful about which rocks you choose, and I would disinfect any branches by soaking in a dilute bleach solution as bark is the perfect place for fungus to hang out just waiting to infect the terrarium.