Hello Jason, here's the answers to your questions:

1) will it come powder coated or painted? It will have a 2 stage powder coating, the first one a Gray primer and a black finish
2) is it possible to either make the windscreen sit more flush to the roof, increase the overall height, or adjust the windscreen down to roof level? No, the problem with wind deflector that touch the surface of the roof is that they rub and with time blemish the paint
3) what is the construction material? is it aluminum (hopefully)? Steel frame / Aluminum wind deflector
4) is it possible to get one with an expanded sheet floor instead of crossbars? We haven't consider expanded metal but we can definitely offer that option
5) cost? Around $700

Thank you

Sergio