Spacing between staves / page margins

[Dominic Sacré]

Hi all,

I have a piece with one GrandStaff containing two Staffs. Now I'm looking 
for a way to reduce the distance between the staves, because there's too 
much unused space, and if I could reduce it, I could easily fit at least 
one more line on the same page.
I know I can use interscoreline in the paper block to change the distance 
between two systems, but what about the distance between two staves in 
the same system, how can I change that?

Also, how can I set the margins of the page? I know about linewidth, but 
what if I need for instance 25mm on the left, but only 10mm on the right?

I'm using a recent CVS version of lily by the way.

Thanks,
    Dominic