http://warlight.net/SinglePlayer?PreviewMap=36650

Should I add diagonal borders between squares? And if so, should the two territories, as indicated by a gold line, border?

It's a fictional world but I may stop it because the borders might be to confusing for players...?

no

It depends on what you'd rather have. If those 2 connect, then all diagonals should connect.

as you have only squares, there will be no problem with diagonal borders, in my opinion. Id rather say that no diagonal borders would be weird.

By the way, how is your fancy 3D space map doing? Id be excited to see some progress =)

Edited 9/28/2014 23:10:13

Well my main project is http://warlight.net/SinglePlayer?PreviewMap=34822
and the one I posted here is my side one... The space one is my third so that probably won't be out for a long time. And as of right now, I'm having alot of troubles with it and can't garuntee that it'll ever be finished...