Great write-up - I did a cooling system overhaul on our X3 this weekend and the photos were helpful. I found the source of an oil leak while disassembling parts in the engine bay - the notorious oil filter housing gasket. My recommendation to others: if you're going to the effort to do this job and you have an oil leak from that area, it's not much more work to replace it. It's an expensive job if you have an indy or dealer replace it ($400-800 is a typical range) due to the amount of labor hours required to access the part. Save yourself some money and replace this $5 part while you're in there and check your CCV/hoses as well.
BMWs currently in the garage: VF570 E46 M3, E46 XI Touring, E83 X3 "M" retrofit