Are B5 S4s covered under that control arm recall?
 

If they are, would they cover it if you had a lowered suspension?

Yup, they're covered. Depends on the dealer.
 

Mine (Agincourt) mentioned nothing about my suspension- I'm lowered by around 1.5" with kw coilovers. But then again, I get along really well with one of the service reps.

What should I do if I am the second owner? I did not get any letter yet. but has a 2000 A4

You dont need one.
 

I just called them up and they knew about it. But I printed of a copy similar to this and gave it to them just in case. :

<img src="http://www.robsaudiworld.com/recall1.jpg">

Just called Audi and they check my VIN said it was ok.

any dealer should cover it