We develop with Visual Studio 2010 (in C#) and migrated a while ago from SVN to GIT. Now we try to split up our repository (which is quite big - ~30.000 files) to many git repos
IF you go down the route of package management, consider OpenWrap. However, embedding the package management artefacts in source code is a bad idea. You can use such tools to update what is actually stored in submodules, but don't rely on them at build time. Expect the binaries to be there from the point of view of your build scripts.