Nokia C2-02 - When using Twitter for Nokia, can I post a photo with my Tweet?

Yes, you can post photos from Gallery.

Posting a photo directly from your phone camera is supported starting from Asha 205/206 PR2 and all new phones launching after the Asha 205 and 206.  Posting a photo directly from camera is not available for Asha 308/308/205/206 PR1.