First of all, the question was about the prepotting. And yes prepotting does a huge difference on boss fights.
2. It's you, who is trying to be a smartass. Tricks are cast before pull (it doesn't mean you cast it 5 minutes b4 tank pulls). So the tank gets 15% boost and builds aggro faster.
3. Rogue should be prepotting haste.
4. Sotp trolling.