Well, you're right about the alpha channel. In Photoshop, create the alpha, and anything you want to show up has to be 100% white. Anything you don't want has to be 100% black. Then, anything in between will be in grayscale, depending on how much of a fade you want. So, in essence, for your bump, the lighter (closer to white) the detail is, the more of a bump you will get. Then, as you said, save as a tiff and import it into the shader in Maya.

But, there may be some other tricks, I'm, by far, not an expert. I just noticed that you said you were pressed for time, so I wanted to try and help out as much as I could.

ABout the fog and stuff, I can't really help you there, but I wouldn't mind learning that myself :p