Hi, I will be your hero if you haven't finded any mod. In first, Witchery to have cities, with walls, ans soldiers. Just add Helpful Villagers, it allow you to "control" villagers, add soldiers and few professions. And to finish this village: Revamp! It modify villager's AI, give them a better pathfinding, go read the thread, you will love it!
More, but you do not clearly asked for it : Epic Siege Mod! It modifys monster's AI, like zombies breaking blocks and many others features...
And to have reals monsters: Special AI and Special Mobs. The first give little powers to mobs (like healing others, spawning...) and the second give multiple kind of monsters (dirt creeper, fire creeper, sniper skeleton). Add Battlegear 2 to make skeletons have specials arrows!