Name these parts... trying to fix leaks

[Balavay]

2005 X5 4.8is, 70k miles. I've changed my leaking oil pressure switch and after that noticed that there is still a leak (or two) somewhere. Pictures were taken on the passenger side with me laying on the ground and looking up. Picture 2 is the close up version of picture 1.

Questions:
1. What is the shiny round part that has some oil on it (labeled #1)?
2. What is the hose that seems to have a leak (labeled #2), is it power steering?
3. Any idea where the oil drip labeled #3 could be coming from?
4. And finally, is that the transmission oil cooler labeled as #4, and if so, anyone know the part #?

Thanks in advance all!