Ouch! I think yours' a new record for correct quiz response time. SunvisorFlyer, I commend you! Here are the answers based on several sources including official North American Aviation records-(don't ask how I got them.)
1a. North American Aviation. 1b. NA-120/-123/-144/-149/-150, XP-82-/XP-82A (as the P-82Z production was cancelled)/P-82B/C/D, F-82E/F/G/H. 1c. F-82G. 1d. TWIN MUSTANG. (Could be flown from either cockpit).
2a. Lt. William G. Hudson, pilot. 2b. 68th All-Weather Fighter Squadron assigned to the Fifth Air Force of the U.S. Air Force. Enemy shoot down occurred over North Korea on 27 June 1950 (the conflict started on 25 June 1950). Lt. Carl Fraser was the pilot/radar operator in the other cockpit and they based out of Itazuke Air Base in Japan.
3. On 28 February 1947 an NAA P-82B Twin Mustang 44-651168 "Betty Jo" not "Joe" once incorrectly marked, piloted by LtCol. Robert Thacker and Lt. John Ard flew the V-1610 Merlins-powered Twin Mustang from Hickam Field in Honolulu, Hawaii non-stop non-refueled to New York's LaGuardia Field in 14 hours, 32 minutes at average speed of about 342 mph. The aircraft had four external fuel drop tanks of 310 gallons each in addition to normal onboard fuel. This set a record for longest non-stop flight by a propeller-driven fighter aircraft of 5,000 miles.
4. 273 total aircraft is correct, and surprising to many in past discussions.
Most built (100) were the NA-144 F-82E TWIN MUSTANGs, so I enclose those specs only.
F-82E TWIN MUSTANG specs
Power one Allison V-1710--143 right-hand and one Allison V-1710-145 left-hand counter-rotating liquid-cooled 12 cylinder vee engines of 1,600 hp each.
Wingspan: 51'2.75"
Length: 38'3" (F-82F/G/H differed)
Height: 13'10"
Wing are: 408 sq ft.
Weight empty: 14,900 lb (others differed)
Weight loaded: 20,741 loaded (others differed)
Fuel: 576 gallons plus two 310 gallon drop tanks
Cruise speed: 227 mph
Max speed: 482 mph
Landing: 102 mph
Rate of climb: 4,700 ft/min
Service ceiling: 40,000 ft
Range: 2,240-2,700 miles
Armament
Six 0.50-in machine guns in wing center section. Optional underwing pod with eight 0.50s; five launchers with five 5-inch HVAR rockets each; racks for four 1,000-lb or two 2,000 lb bombs.