A: Google Base Feed is actually an advanced RSS feed. All the extra google base fields are just hidden from the rss but they work the same.
OpenCart's googlebase/rss feed is listed under the Extensions->Feeds section of the admin
1. Install Google Base feed
2. Edit it and copy the url
You can link to this url directly to see an RSS feed in your browser.
You can also use this url for your Google Base scheduled updater.
Note: Google Chrome does not have an RSS reader built-in by default. You need this addon for that
Google Base / Merchant Center
Here is a screencast on using the Google Base (aka Merchant Center) scheduler with the google base url from opencart:
http://screencast.com/t/nTzGvmouk
Note that even tho you create a filename like "data_feed.txt" you never really need to worry about that as the url is for the scheduler. You only need to use a file called "data_feed.txt" if you are manually uploading.
The Google base scheduler can be set for Daily updates and will automatically go out and grab your feed once per day. You should never need to worry about it again. However, if you choose that you'd like to manually upload the file, you can load the url in a browser like Firefox or IE and save the page as "data_feed.txt" and then upload that file manually.
Troubleshooting
If you are unable to load your RSS feed directly in your browser or are getting errors, your best tool for finding the problem is Internet Explorer. It is the only browser that actually shows you where the error is.
Now the error still seems a bit cryptic but it tells you the line and char number. If you view the source and open it with a good editor like Notepad++, you can see line number and character (column) numbers and spot the issue:
In this case, the "&" is only a problem because I forced the error. Normally you should not have a problem with & in 1.5.2 and later.
