These ideas are very good
I agree with the above ideas very much in fact i think all of these should be essential for a game like this. It will just make the game even better and yes it will add to the epic-ness of the game.
Also another idea would be the type of map and the effectiveness of the a nations in that area. Like for example Elves should gain a environmental defensive bonus in the forests and etc and humans in naturally viable locations, not like volcanic areas hence they would receive some negative effects. Orcs can be the hardy type and have bonuses in Dessert type lands and get a negative effect when in forests etc.
That it the environmental effects, weather effects can also play a part in the game that being said it could contribute to the dynamic effects the game is suppose to have.