The II is a double slot.
I'd get the Asus, and not bother with the TOP version. If you'r case has good enough air flow you can have the fans slow enough for it to be silent.
Correct.. Newer Asus DirectCU II cards are double slotted..
If you're Running it on 3 monitors? I would suggest buying 4GB version cause when gaming on 1080p triple monitor setups would consume roughly 2GB+ VRAM usage..