As to the arena thing...
Perhaps a penalty should be assesed to nations that don't enter the arena, futher penalties could be assesed depending on how well your champions does. Loses right away your people get more unrest, wins the whole thing, unrest goes down, or extra cash is raised... somethings like that.
This way it makes sense for every nation to start training arena competators (at least to some extent) otherwise they can get hit in their economy. Heh if you want to be really cruel give curses to all commanders of a nation that doesn't send a representative to the arena
