OP, in the 1000-1500 range I'd consider the Bilstein B14, stainless steel housings with aluminum plates. As for the sleeve, you must be referring to the coilover condoms
They'll help a bit I suppose. Don't know if they affect road/suspension noise or not. Personally I have never used them, because even if you do, you have to take them off occasionally to spray off any moisture or salt that happens to sneak in there anyway. I think as long as you clean your coilovers regularly you will be fine.
Cheers!