This may be a bit off topic (I'm replying specifically to your question about source control and graphics), but you can put binary data (images etc.) into source control (and in my opinion in a lot of cases should) -- they just take up more disk space and you can't use a diff view to analyze what has changed in any meaningful way, but what you do gain is a history of commit messages documenting each revision, rollback ability and the ability to easily archive (tagging a revision in SVN terms) all files (be they visual assets, documentation, source code, whatever) belonging to a specific release/version together. It's also easier for your build system to just fetch everything required for building a specific version of your software from the source control.
