R0022A.3AM (Buell 1125 Clutch cover Assembly w/ needle)
Q0428.3AM Water pump shaft
CB0028.1AM Thrust Washer
E0015.1AM Needle Bushing (not needed if you buy the cover, it should already be installed)
Q0430.3AM Oil Seal
Q0431.3AM Rotary Seal
Yes to re-using the impeller unless it's damaged. They're cheap enough, I'd just get a new one.
An additional set of tools that may be "helpful" are in this list. I didn't use them myself, just a small press and the correct diameter hunk of aluminum.
WATER PUMP SEAL INSTALLER BASE TOOL (B-49141-4)
WATER PUMP OIL SEAL INSTALLER {B-49141-2)
WATER PUMP WATER SEAL INSTALLER (B-49141-3)
I don't have any discounts running at this time.