While in Pages and Syllabus, I uploaded a Google Document from my Google Drive, but was unable to edit it while in Canvas. Is it true that once I upload a document from another file, it can not be edited in Canvas? Also, there does not seem to be an upload capability from Google Drive when in Canvas Folders and Discussions. Is this accurate?
Files that you upload can't be edited, correct—the editable "documents" in Canvas are the Pages. Anything you bring in from an outside source isn't able to be edited within Canvas; it has to be downloaded and reuploaded. (I'll let someone else handle your other question, since I have no experience with Google/Canvas compatibility.)