Chord Progressions and Key(s) within First Song

I'm working on a song>

I have a short intro: G Em G Em (times 4)

The verse progression is

Cmaj9--->C---->Cmaj7---Em
Fmaj9---->Fmaj7----------Em

The chorus progression is in the key of G:

G---C----D-----Em (four times)

It ends with a repeat of the intro.

I started out without an intro. I liked the verse progression because it followed the melody line beautifully. (I-iii-IV-iii) (And because the Fmaj 7 to the Em captures the mood exactly) But if I used only the verse progression (without establishing some kind of sense of the key of G in the intro), would the song be in the key of C? The verse progression being I-IV-iii. And if it was in the key of C, would it be ok to have a chorus in the key of G (being I-IV-V-vi).

I hope this is not a stupid question. (if it is , it is not the first!) I can't wait to finalize the lyrics; as it sounds good to me.

This is my first song.

Ghost 8)