Probably better to ask this in the ROM forum. I'm not fully familiar with the mod but it may use flavour starts, so if you are using the same Civ each game it might generate relatively similar starting areas like tundra/forest/deer. Greece seems to get that a lot for me in the vanilla game.
As for Worldbuilder, it is the map editor that you can open from the in-game menu and change resources on tiles. Considered cheating, of course, but you can do anything on your own for fun if you wish.