Definitely DON'T use gradients on the masks. The masks must remain all white.
Use as many gradient layers as you need. Maybe you'll wish to put them on a blend mode, such as "Multiply" or "Screen", but in some cases "Normal" mode will be fine.
Make sure you make good use of transparency in the gradients.
I want to help you more, I really do, but I need to see what you have in mind.
DO NOT USE MASKS. I can't stress this enough.