The fastest subsonic jetliner is the Convair 990. However, the DC-8 was the first supersonic commercial jetliner when it reached mach 1.012 on a dive over California on a test flight in the early 60s.
The four engined airline that flew with five engine was a testbed Boeing 707 for an engine manufacturer (I forget which) with a fifth engine mounted on a horizontal strut off the right hand side of the nose.
(If this isn't the answer you wanted, its still an answer!)
E-3 is a Boeing 707 with a radome on the top.
E-4 is a twin turboprop engine carrier-based radome-equipped airliner.
E-6 is a 767 for the Japanese Air Force used in the same way as the E-3 for the USAF. (not always equipped with a radome)
The length of the A318 will be..... even shorter than the A319??????