I believe that "Visit Start Page" and "Visit Start Page Url" are the values of the page name and the url for the first page in any session....
You're right that I don't see this available in Workspace or in Segment Builder, but based on your comment, I'm not sure if you need to create a segment for them, but rather, just included them in your Data Warehouse export while using your country segments?
However, it seems to me that you would end up with a lot of repeated info, showing the "first values of the visit" for every hit in the same visit... But I guess it really depends what you are exporting.
I think that maybe "Entry Page" is the Workspace equivalent to the "Visit Start Page"... but as we know, the raw URL fields aren't available in workspace.. if you want to see the URL in your own reports you need to create an eVar (or a prop, but the 100 character limit causes some challenges there)....
It might be worth doing some one day exports to see what kind of data you are getting, and if it's the expected values?