Gimpdome

Gmorning all

I'm trying to learn how to model and UV map in Blender and would like some general advice.  I've made my model and got it unwrapped (its a scuba mask  ) and I saved a black and white image of the layout and I'm painting away in GIMP...

1) should my paint layers have a tranparent background or will that mess me up if I leave a hole or even just too have alphas in my texture?
2) for that matter, can you even have an alpha layer for a texture that is going to be UV wrapped?
3) my scuba mask has a translucent skirt and a transparent glass material and I'm not sure how to handle that.  Should I make a layermask and save that with my main material - if so any ideas how to use it so that transparancy is handled by the alpha layer rather than color?  OR should I make a seperate layermask greyscale image and import that as a seperate texture and make the material from these textures within Blender?
4) In general, how should I handle edges where colors change dramaticly? e.g. I have a blue fram that sits on the whitish skirt, should I feather/ fade the interface or try to make it sharp?
5)  Those lines, hmmmm, I know that they are only one pixel wide but do I paint over them - or paint up to them, or up to them with one color and over them with the next, or fade the edge and overlap the colors?

any other words of advice to the novice?

OK I learned several things today and just posted them on Blender Underground (in a nutshell 1) think of UV as nothing but a map of where your faces will extract the info from the texture that you apply in materials! 2) alpha map texture is simple just use calc alpha, apply it as alpha, fiddle with the mode, the alpha setting on the material determines just how transparent absolute black can get in alpha texture -> its set to 1.0 so alpha by default doesn't work!  3) subsurf muddles everything and causes jaggies!)

BUT all the other stuff on making these textures, all the "tricks" if you will I still would love to hear any advice you may have.

In my limited experience, decal pastes last on top  of everything below so that it is independent of the texture.  Oh and I didn't understand until I figured out that you use a camera to project the decal onto the surface so angle and orientation are defined by the camera that is holding the decal.