Hope there's more than just the clamp securing the heat lamp, as clamps are known for failing. Hard to see in the photo, but just putting it out there as a PSA.
Pretty much from the start, though they're so tiny at the beginning, you probably wouldn't notice the dust until later on, when it's noticeably built up.
FYI do not rely on the lamp's clamp to hold... they're well known for failing. I would suggest securely wiring the hang loop on the lamp to the clamped extension arm you're using to currently support the heat lamp.
Sounds perfect then! I figure if/when my current brooder finally falls apart, I'd get one of these rabbit hutch style units to serve as the next brooder.
Only thing I'd caution you about is the newspaper as the flooring, it can get slippery and contribute to splayed legs (even if you haven't had issues with it, I'd encourage others to look for a safer flooring). And I'd cut a couple windows in it, since once you take it outside it's going to be...
For heat I use a mama heating pad which gets disassembled after use.
For bedding, I use my deep litter run floor. Rake it up in a pile, sprinkle a bit of wood shavings to make it fluffier, plop the brooder on top, and done. Zero clean up, zero odor. To "clean" it I simply move the brooder...