1.Mordekaiser has no CC. Mordekaiser can do big damages but he's not a tank. He can't replace the tank on your team. Don't even know why you'd bring him up.
You don't have any clue what "meta" means, do you. Push your lane, farm jungle camps, make sure you're ready for team fights. That's one of the two major roles of mid in the "meta". How is this any different from MordeKaiser, Karthus, Anivia, Orianna, or any other farmfest mid champ? You're either farming the crap out of your lane so that you are good in team fights, or you're pushing your lane so that you can roam and gank. Nasus fits into the former category without any stretch of the imagination whatsoever.
Hell, people are running AD bruisers mid now; Nasus is almost more "meta" now than he was before.
2.That is apart of the meta. But meta also includes team comps and strategies. Most of you have never had to worry about team comps or strategies, you just pick the champions you want and make sure to have a tank and an ad carry. Nasus changes the meta because he allows someone like Kayle/Tryndamere/Gangplank to go into the jungle and build carry, thus giving your team 2 hard carrys late game. You can also throw an assassin top because Nasus frees up so much for your team.
3.No one runs AD bruisers mid. They run AD Assassins. Kha'Zix, Pantheon, Lee Sin are all AD Asssassins. Jarvan can go mid but he also builds like an assassin because Jarvan is a very strong assassin.
4.You actually max Q first. You just need enough levels in E to one shot the wave. For some people that's Level 3 for others it's Level 4. The second you can clear waves with one E is when you start maxing Q for the cooldown. Wither is strong regardless of the level.
--- Realo won gold at the Sex Olympics with a BROKEN FRIGGIN NECK.-Voltch
I'll explain once again since apparently people read as poorly on this board as they do Board 8.
Nasus breaks the Meta by opening up team composition. AP Nasus is one of the only champions in the game with AOE Magic Damage, legitimate tankiness, strong CC, and sustainable burst. The rest of the AP Tanks are junglers like Amumu.
By having your tank double as your AP Carry you can send carrys and assassins in the jungle and top lane while not losing team unity.
There's a reason you don't see Tryndamere and Gangplank jungle in high level games even though both are VERY strong in the jungle. It's because doing so forces your team to run a tanky initiator top lane which puts a strangle hold on counter picks. It's easier to just throw a tank in the jungle where he has no fear of losing a lane.
Realo won gold at the Sex Olympics with a BROKEN FRIGGIN NECK.-Voltch