Hello: I just got done reading this thread and thought I would offer my thoughts. The thoughts & advice that follow are not necessarily the "right thing to do" but merely what I would do if in your situation.
1.) I would wrap 3 of the 4 exterior walls of the terrarium with a highly reflective surface (mylar, panda film, orca film, etc.). I might consider wrapping all 4 sides, but making one (or more) of them removable so that I could view it from different angles.
2.) I would just purchase a fluorescent bulb of some variety to rest on top (or hang above) the terrarium. Given that you want to grow the plants to their fullest potential, I'd recommend T5-HO's. Seems to me like you would only need a 1 or 2 bulb fixture w/ a reflector.
3.) I would NOT include so many different varieties of plants in there right away. I'd start with moisture loving plants such as Drosera and Utricularia...keep them alive for a while...and then slowly make changes. Treat this as though you're setting up a beautiful aquarium- set it up, let it stabilize, monitor results, and slowly make changes/additions.
4.) I would NOT include plants that require seasonal changes such as mexican pinguicula, VFT's, Sarracenia, pygmy sundews, etc.
5.) Don't completely cover the top of the terrarium, allow space for air to move. I'm concerned that you're going to develop a mold situation. If I allow my air around the plants to get stagnant, even if they catch a TINY fungus gnat, it sometimes can get moldy. Even just a small oscillating fan blowing around the room works wonders.
6.) Regarding the design and types of plants...I would probably try to grow D. capensis varieties in the back because they'll get the tallest...then in the front half I would grow all sorts of shorter sub-tropical Drosera, mixed among terrestrial Utricularia. I grow lots of sundews here in New York and my humidity in the winter hovers between 20-50%, and the plants are full of dew. Get the lighting and water needs right first. Just remember that these plants go through shock, and don't always look like they're improving right away. It can take some time to see whether what you're doing is helping or hurting. Which again is why I suggest working solely with easily obtainable and forgiving plants first before making the terrarium more complex. Honestly I'd probably plant Capensis in the background, other shorter varieties in the foreground, and then maybe even get a bunch of different types of seed, throw it in there and see what happens!