Changing fonts

[Noeck]

Hi,

I can change fonts like this:

\paper {
  myStaffSize = #19.0
  fonts = #(make-pango-font-tree
            "Linux Libertine O"
            "Linux Biolinum O"
            "Ubuntu Mono"
            (/ myStaffSize 20))
}

But that way I always need to specify the staff size. However, I would
like to put this in a style sheet and set the staff size later in a
file. Is that possible?

Or is it possible to read in the global staff size?
Or could #(set-global-staff-size ) be changed in a way that it also does
this change for the fonts? -- In short is there any way?

TIA
Joram