Google Drive – Using Google Docs for File Sharing

actually it's enough to uncheck "convert to google document" and upload it in the original format without conversion.

Changing the filename did not work for me when I renamed to ".jpg" and then renamed the uploaded document back. I could upload and rename, but the filetype was still identified as "jpeg" and on download the file extension was reset to "jpg" (which could be quite confusing for other people you share it with)

Buried in the help pages for Google docs I did find a page that discusses uploading multiple versions of a file

You can upload different versions of the same file to your Documents List and easily keep track of them by selecting the Add or manage versions... option (or View versions... if you have viewing permission only).

This feature lets you upload new versions of a file, as well as download previous versions of it, and delete older versions. It makes it easier overall to collaborate on a file with other people. Each version counts toward your total Google Docs storage quota, so you should clean out older versions every once in a while.

This feature is available for uploaded files that are not in Google Docs format. For Google Docs, you can use the revision history, which lets you see all the different versions of a doc.