Self leveling = front coil springs and rear air springs.
Air suspension = air springs at all 4 corners. There have been a few posts regarding what was standard on the 3.0 vs 4.4 vs 4.6/8.
FYI - my Eibach kit came with 4 coil springs, so make sure you only order the 2 spring version with rear air suspension. H&R and another member here sell
adjustable rear endlinks that will trick the computer into lowering the rear to match new Eibach or HR springs. I paid the dealer 75 bucks to lower mine via DIS computer.
The first pneumatic air spring that went out cost me 800 for the dealer to replace. The second one I did myself for only 300 in parts. My dealer stocks the pneumatic air springs but not any of the air tubes. According to my parts guy this gives you a pretty good idea of what commonly fails according to whats in stock.
The front spring job was much more time intensive and requires a ball joint removal tool because you will also want to replace the front control arm bushings while everything is apart. I spent about 4 hours on mine with air tools. There are several write ups on the front page of this website.
Good luck Eric in AZ