Is it a mistake on your part that you've listed the same GPUs in your planned rig section?

if not then here goes:
1. Ogrimmar is heavily CPU reliant meaning that at your current settings you will get better fps there but it won't increase much everywhere else.
2. i7 2600 is not a particularly hot CPU, so no watercooling would be wasted effort especially at stock speeds.
3. Well since you are upgrading the CPU and not the GPU no, there won't be a bottleneck.
4. Adding an additional display won't hurt.