[peterb]

Having some descent knowledge of licenses and law (law school student) I'd like to throw in my 2c.

If you want to keep the project accessible to as many as possible I would go for GNU GPL. While the Creative Commons licenses have been specifically designed for works other that sourcecode and works very well, the CC licenses lack one feature that (IMHO) would be important in a project such as this and that is access to the "source". Even if you publish PDF-files that are easy to print people that wants to build upon your material will need the raw text in a word-processor format. You will also want to have easy access to the creations of those that spin off from this project and the GPL enables you to request the source and CC licenses don't (nor does the OGL). So I would recommend you to go with GPL.

As for splitting Setting and Rules. That's probably a good idea - design wise. Statblocks aren't really copyrightable nor are rules as such so there's no real reason - legally speaking - to separate the two but it's probably a good idea out of practical reason. When designing computer software the mechanics (the code) is as much as it's possible separated from the user interface so that the UI designers can work without having to bother with the doings of the coders. Having a setting with all the details needed for play would enable people to use the setting with their favourite system. Which would make your material much more useful and allow you to target at wider audience.

/Peter Brink