The bulk oil filler is a device that uses the tank, a dial and a small pump. I guess Bluebird didn't want the owners to get dirty adding oil to the engine. All 4 of my Bluebirds had this feature. If you need to add a quart of oil, you move the pointer on the dial, turn the unit on and wait till it dispenses the oil.
The 300 amp alternator is so large that it could not cool itself enough with just the small fins so they used oil.
Bluebird, back in the day was all about redundancy- extra systems added to the coach- and the price was reflected in all the extra goodies you could add. Each coach was custom made- no 2 coaches were the same.