OK, I'm not one the CWBP experts, just a participant, however...
1. Each block is approximately 600 x 600 miles. Note these are longitudenal lines north to south and they do converge closer together the further north you go, so these aren't true blocks.Still most of the map squares have been created at 600 x 600, however.
2. The actual FT created world we chose to use for the CWBP includes several continents. We didn't want to start the project all over the place, so we focused on one of the larger continents. The regions are only of the northwest half/quarter of the current continent. We haven't even opened those regions yet. At the moment, we are populated the existing regions.
3. The world was FT generated, thus pretty much push button. Not that someone shouldn't create a reasonable plate tectonics map that could justify the current geography, this method wasn't approached at the start of the project.
Someone, (NeonKnight, I believe) created a dozen or so random FT terrain maps and we posted a poll to vote, which one to take. We picked this one and that's how the project started. We weren't all that scientific about it.