Front and rears are slightly different. IIRC the rears are shorter than the front, but could be the other way round. If you have all 4, the pairs are probably mixed up.
News to me. I've been through 2 sets across 3 AW's and a set for my SW and even had a warranty replacement. Never noticed it on the instructions myself but cannot say I've read them through. Every time they just dropped in and worked. I have a set of aw fronts still in the box somewhere... I'm going to have to look next time I see them. All my AW's were early, 2x'86 and an '85The weird thing is, it's what KONI suggest you would do for the AW11 (I know, I called them). In a lot of cases the insert is to tall and you can grind a few mm of the nub. There seem to be 2 marginaly different struts, so they made that stub. It seems to be what it's there for.