1007 - Electric layouts

Hello,
I own a 1.4 Hdi Happy 1007 and I'm very satisfied of it.

I would like to make 3 modifications and I'm going to ask your help:

1) Boring belt beep beep... Can I pull the beeper off of something like that
(cut the wire, fusibles)?
2) I've electric windows controls that are not "automatic". I would like to
push the button once and the windows go up and down by themselves, till the
end. Any idea? Can I simply change the switches or it is more difficoult?
3) I would like to add the rear speakers. Do you know if the cables are
already present and the speaker sizes?

Thanks in advance
Qbert