Firstly, I've been in just your situation - the door panel is surprising very well screwed together! There are quite a few screws to remove. From memory you need to locate and remove the following:
- One on the triangular plastic cover at the front top of the door, next to the mirror;
- One behind the door lever;
- One behind the electric window switches (which just prises out);
- Two on the edge of the front (hinge) side of the door panel;
- Two securing the door pocket at the bottom;
- Two located at the very bottom of the door panel;
- Two behind the speaker cover.
The two behind the speaker cover are probably the hardest to locate, but they are there!
There may still be more screws. I'm sure I find a couple more every time I take the panel off! If you still can't get the panel off, I'll go and have a proper look at mine.
When you get the panel off, there's should also be a foam/plastic weather protection seal on the door which you'll need to carefully remove to get full access to the door internals.
In answer to your second question, I don't know - it depends what the noise is! However, there are quite a few yellow clips holding various bits of wire and cables in place. They had worked loose on my car (or not been put back properly by the dealer
) and were rattling around a lot. I've fitted them all back into their respective slots and have successfully got rid of all the rattles, so there's a good chance you might be lucky!
Anyway... good luck!