1. Magic: No.
2. Races: Humans.
3. Custom Universe
3.1: Create a custom planet that is Earth-like but is different in terms of geography (different continents, bigger/smaller oceans, etc), history (former empires, old wars, etc) and technology. Have it set in a time period that we can relate to (Age of Discovery, Pre-History, Birth of Civilisation). Kind of like Sid Meirs Civilisation except with custom nations. 
4.1: Negative.
4.2: Own nation.
4.3: See above.
5.1: No. In the case of arguments over wars, it should be resolved by the people involved in it and if that doesn't work, get the OP involved. I've never been in a nation RP that has ended in arguments over wars, mainly because war adds to a great story telling. 
5.2 Free form.
6. Absolutely negative. Let the RP'ers figure out their own story lines. Dice makes it feel like a game.