i can help you only for the last question :
"P.S. I suppose that installation from source is just ./configure, make, make install of each archive?"
Every source package has an INSTALL file that tells you how to make the correct installation, but different source packages may have different formality of installation. A lot of packages can be compiled with 'configure make install' procedure, but some packages doesn't follow this rule.
You can see this web-page :
It has a complete set of instructions to install Gnome from source, but as you can see ,it's not updated to Gnome 2.6 yet... i'm awaiting for that too.