Where would this indoor enclosure be? If it's in an area thats conditioned you are probably overthinking it, but it's better than under thinking it. Radiant heat panels are prob way to go for ambient heating in indoor enclosure. If its in an unconditioned space, like garage, then what you're...
UV-open seems to be a newer term. UV transmitting might yield better results. The acrylic sheets were originally used mostly for tanning beds so searching in that direction might also help.
Example of acrylic sheet...
No, not all greenhouse materials are UV open or UV transmissive. You can get panels that are also UV open but in my experience they've usually been more expensive and harder to find. And the shipping on the panels is usually expensive because of the size.
Here's an example of a cold frame by...
I think this video shows the size well. Especially around the 15:00 mark, the CMUs give a good idea of the size since they are a standard size (8"x8"x16"). I didn't particularly like the setup he went with, and I muted the video because he seemed annoying so I can't say anything about the...
The corrugated panels (first link) will roll up on themselves more if unsupported, but the panels Mike used (second link) don't bend as much. Regardless, screwing to posts should keep the panels where you want them.
I don't see a benefit or anything made easier by using the roofing panels...
It really depends on what they mean by 'telephone poles.' If the ground is on the sandier side, I can see how larger diameter poles or longer poles that can be placed deeper might be better. So it might be better for your location. But even shorter sections of the poles would be heavier and more...
It's up to you whether you want to use that lamp until it stop producing UVB or replace now. It been a while since I saw the test results with Repti Zoo bulbs, but I think the spectrum wasn't ideal though not necessarily dangerous, ie more shorter wave than sun/other bulbs but not nonterrestrial...