What kind of "why" do you expect? There is a pretty large collection of computers, network equipment, UPS and HVAC stuff. You want a machine per machine watt usage?
It's a due diligence kind of thing. If you're asking people to make significant monetary contributions, it makes sense to provide a clear picture of what you're using that money on.
Exactly. Donors of non-profits like to see where the money is going. If you're doing an arms length transaction, then it's ok to say "No need to look behind the curtain, and feel free to buy from someone else."
8 year old image of one of the racks, is only grew since... http://www.openbsd.org/images/newrack.jpg