I'm wondering if I should bother mastering my mix in audacity. I've already EQ'ed and leveled it pretty well while mixing, so should I tamper with compressors/limiters etc, or should I just let it be? If I don't do any compression, should I normalize it to bring it up to the loudest possible level? Apologies if this thread has been made before.

Honestly, I believe you should let it be. The individual tracks are already mastered/compressed/etc. Get your levels right when you mix it and you should be good.