Hi,
1. Typically with Eibach springs you won't get that drastic of a drop to cause any issues with rubbing on speed bumps (unless you have "speed mountains"

) Hence i would not worry about that.
You also need to remember that there is a lip at the bottom of the aerokit ( & standard) bumper than hangs fairly low. This will be the first thing that will rub on anything and it sounds much worse than it really is. We find this to be more of an "issue" on coilovered cars with a 40-50mm drop.
2. Koni FSD's will definitely improve the ride quality with the Eibach, they are far more superior to the standard damper due to their design. The dampers wont have any effect on ground clearance and hence you are no more/less likely to hit any speed bumps with the dampers than you are with without them.
3. Yes we can fit the Eibach springs you have already purchased if you were to go for the FSD dampers.
The rest of the answers on a PM.
Andrey