difficulty

[vartan]

You can play on any difficulty, though the recommended is H/M I believe. Playing VH campaign will make the AI go berserk on you and it is nigh impossible to have peace with any neighboring factions. VH battle difficulty makes the AI's troops have much higher morale, armor, etc..., which means that levy troops can sometimes defeat troops much better than them. Very annoying. And of course, you could always play on easier difficulties than the recommended, which will make the game...well... easier. But AFAIK changing the difficulty doesn't mess with the game script.

Recommended for EB: VH/M.
If you have balls the size of Mt Olympus: VH/VH.

[Titus Marcellus Scato]

I would suggest picking the difficulty level that suits your preferred playing style.

If you want constant battles against stack after stack of enemies, and blitzkreiging the map, pick VH campaign.

If you want a basically quiet campaign with most turns being peacetime city-building, with occassional wars and battles in between, then pick M or H campaign. This is better for slow, more historical campaigns.