Also, orders are showing up in zen cart admin from GC however when I update those order statuses via ZenCart admin they don't update/change on my GC account. Is this normal as well? Is this addon just a way of notifying you via ZC admin of a new GC orders - with the intention that you do all of the processing work (ie charging, marking as shipped etc) via your GC account??
Order updates made from Zen Cart admin should be sent to the GC accounts (customer and merchant). Make sure you're updating the order using the Google choices from the drop down list. If you get a pink error message in the top of ZC Admin its prob because the GC status you chose was not in the correct order (cant choose refunded before charged, etc.)
Also, GC orders are automatically "archived" after they are updated to *shipped* so check that they are not hiding there.

One more question - how do I find out if my Site is installed with PHP over CGI???

Thanks
I have Godaddy as a host and I know they use PHP over CGI. You can call your host to find out or do a google search for "your host name, php cgi" and I'm sure your search results will yield some relevant info :)