Can I store Itunes media on an external drive and access it from itunes on my C drive?

Not sure about Windows, but on the Mac, you can set the location of the iTunes Library in iTunes’ Preferences.

Yep, this is easy. I’m on a Mac right now and you can change the location under Preferences—> Advanced.

Windows has a similar option.

Yes it’s possible to do the same with Win. Edit>Preferences>Advanced>General

Yes. That’s how I set it up for my mom. And she’s using windows.

If you have an existing itunes library, set the new location for your library as described above. Then click advanced and then consolidate library, I hope that helps, if you want to know more about what you are doing, or ways of having different files in different places or anything else, just ask and I will try my best to explain.