with a normal air suspension set up, the air bags/air sturts do not automatically refill themselves. The reason that struts are "more comfortable" is because they are able to expand when going over a pot hole or whatever may be in or on the road. Air cylinders are not able to expand because it is metal/steel. the struts on other hand, have rubber air bags on them, rubber = flexing and expanding. The newer stuff from air ride technologies is able to level out your ride at the set ride or pressure height, so if one of your struts loses or leaks some air, the computer will automatically refill it, leveling out your ride. The kit you are looking at has some small ass valves, i think 1/4". The bigger the valves the faster the air pumps and dumps, the quicker you can adjust your ride.
As for the different ride heights over speed bumbs depends on how fast your switch finger is as well as how fast your system is. the quicker you switch the less air you allow into the strut, if you want to fill your struts up all the way and get to your max ride height you can sit your finger on the switch and let the strut completly fill. it all depends on how many how much control you want, you may want to only go front and back, or you may want to go front back side to side. I don't know to much about the new computerized leveling system, but with my air ride i was able to get my car pretty level just by seeing how much air pressure i have on the gauges. Although i did love to drive with the rear slammed on the floor, and the front in the sky. The looks i got from people were definently worthy of being a kodak moment. :^
if there is anything else i missed or am wrong about, hopefully some one can correct me. goodluck with everything!!