I just put in the KW springs with the adjustable height with Koni Sport shocks. The Bilstein look similar. The perch (adjustable part) goes on top of the spring, this goes up into the cup on the body. I put the perch in at max height so I could adjust them to a lower height. It looks like the the Bilstein has a greater range. The issue is to adjust the perch you have to compress the spring to get the nut down below the bottom of the cup to turn it! So you can not just put a spanner on it and adjust.
It looks like to have the ability to adjust them easily on the car you would want to go to a coil over shock setup. These are much more expensive. If you are not going to due much tuning on the suspension you might want to chart all the different spring kits and pick the one that lowers the car to your liking. I found about four or five different sets and they all lowered to different heights.
The KW springs front stock NA coupe fender 26 1/4 to 25 3/4 and rear 27 1/2 to 26 1/2 with my perches at max height. I can lower the front 1 inch and the rear 1/2 inch after I put it on the rack and put a spring compressor on each one to get to the adjuster nut!

Good luck!
Dan