I'm feeling a bit had by the common "best" practices in bearded dragon keeping. A scary lot of it is starting to seem so distanced from any genuine understanding that I'm learning all over again.

I want to give my dragon (Pepper) a more comfortable habitat, since I'm feeling like the shelf liner and tidy conditions are a little... not what would really make him happiest. Considering how hard some ends of the dragon community rail against loose anything... am I just projecting?
I'm pretty keen on the idea of a bio active substrate, and have been reading up on it here and elsewhere. I have a rough plan and few questions. My understanding is that the bioactive (Isopods, springtails and micro fauna) are the real added value, and just dirt is not as much benefit, is that accurate? Is a dragon cage a suitable "beginner" project, or would I be better off starting with one of the snakes habitats? I'm guessing it's the same as fish tanks, and the bigger the more stable but maybe the more work to set up.
I have a sealed wood 4x2x2, and will add a liner to protect against moisture. I'm thinking adhesive vinyl or something, sealed in the corners. I need to look up safe materials yet. For soil, I live in the city so my options are bag dirt, or hauling some from my parents place out in the country. They are in an undeveloped area near Lake Michigan so the soil has a high percentage of sand; it's sort of soft, drains well and is free from chemicals. I would amend it with coco husk or top soil (bagged) in the event it's too sandy. I can gather leaf litter, downed logs and probably Isopods at the same area. I'll use hydroton I think for the drainage layer, screen on top then soil blend.
1) Is it worth hauling live dirt? Or am I just as good off with store dirt?
2) How deep would a dragon want the soil? (Need to judge how many buckets I'd need)
3) Does the soil cycle like a fish tank does? How do I keep it from "dieing?"
4) Does it need to establish before the dragon can move in?
5) How are direct life-cycle parasites treated/controlled?
6) What is the bio load capacity of the system once established? Can I starve or over feed it? Well. The dragon not me personally.
7) In the event I need to add ventilation is it better to increase the screen size, or add a fan? I have soffit covers currently, but could easily add different screen or a computer case fan.
8) Do I need to build in access to the drainage layer?
I'm thinking about replacing my incandescent basking bulb with a halogen. I have a 150 incandescent right now. I'm hoping to be able to use a small or mini bulb or set of them to get some height back. It looks like the minis are all too narrow a beam though.
9) How much hotter do they run for equivalent wattages? (50W is not enough, that's all I know)
10) Do I need a ceramic socket or is the metal one I have ok?
Down the road I'd like to upgrade to a T5 fixture (currently T8), considering I have 2' now and will loose probably 6+" to the soil, will I have a distance problem? Pepper uses any vertical space/furniture I give him.
Has anyone tried bioactive and hated it?