I still maintain that section I is in G major, since it resolves via the C-F# tritone (which is basically viidim of Gmaj and a very strong dominant function) to G. It just makes sense, since the next section is in Eminor, and it's a pretty common compositional technique to begin in a certain key and then quickly modulate to the relative major or minor.
Xarthaz, you're absolutely right... I should edit this and try again. I think what happened was I ran into a non-diatonic chord and got confused. I tried to treat it as a temporary modulation but I'm sure it's just a modal borrowing like you suggested.
Edit: It also looks like I screwed up in section 2; this part IS clearly in e minor. So the opening G in this section is treated as the III of eminor and it ends up resolving via a plagal cadence. That makes a heck of a lot more sense.