The only way is for me (or someone!) to provide more images that are the colours you want. That said, I think Gadgets actually ships with a red orb in the library, so it should be really easy to switch over. I'll have a look in a bit to see exactly what you'd need to do.
Yep, it's possible and quite simple to do. The only problem is I think other things are attached to it for positioning, so you'd probably need to adjust these too.
If you have a look in Gadgets/wtLibUnitFrame/Templates/templatename.lua, you should be able to work out how the templates work. Removing the "barResource" element will get rid of the bar, but you'd probably need to adjust the anchors on "barHealth" to attach it to the bottom of the background rather than the top of the resource bar.
If you're struggling, let me know and I'll post a file with the changes applied.
Yep, it's on my list of things I need to get sorted out. It should be easy to add. I'm a little wary of adding another full bar element to the frames which are already fairly heavy on the CPU, so I just need to come up with a lightweight way to handle it.
This is a subject that comes up a lot, and I've had many discussions with Zorba (Trion) about it. Due to limitations enforced by secure mode, we can't change things while we're in combat. I took the decision a long time ago (rightly or wrongly) to not allow the frames to be in an inconsistent state, and instead block out the mouse so that I can always show raid frames correctly, even if they change while you're in combat.
I had hoped Trion would give us a solution to this a long time ago, but it seems to be a difficult fix to put in place. Zorba does tell me this will be implemented, and as soon as it is, Gadgets will be changed. Until then, I'm afraid we're all stuck with huge mouse dead-zones.