Nymia, I am not the person to get the nitty gritty details on rsvg from. If I where you I would contact cinamod who you can get hold of in the #abiword channel on irc.gimp.net using the nick ‘dom’, he is current maintainer.
Since you have seen the code you probably now the basics, that is made using ANSI C and that it only dependency is afaik libart. If you have GNOME stuff installed it will create a SVG pixbuf loader and a gtk theme engine for you also. After Dom’s latest updates it is getting rather full featured and it will mean that GNOME 2.2 can use SVG graphics pretty much anywhere in the GUI. The code was originally created by raph as part of some contract work for Eazel.