Greetings John!
Welcome to the world of Vintage Airstream ownership!
I can't help with all of your questions, but I can with this much
information.
You coach should be pre-wired for air conditioning and the drip tube should
be pre-installed. Airstream did not install its air conditioners in
existing vent openings, rather the necessary opening was cut a measured
distance from the number one roof bow (where front dome meets the main roof
panel on exterior of coach) to the rear - - the opening was then made at
that point - - bracing, wiring, and condesate drain would all be in that
location. Your Airstream Dealer should be able to assist with the placement
measurements for the air conditioning unit, or customer support at the
factory (http://www.airstream.com).
A double-check to be sure that your coach was pre-wired is to check the
circuit breaker panel or fuse box - - there should be an extra unused
circuit that was provided when coaches were pre-wired - - it is my
understanding that all Airstreams were pre-wired beginning in the
mid-1960s - - I know that my '64 Overlander International was pre-wired.
Kevin D. Allen
WBCCI/VAC/Free Wheelers #6359
1964 Overlander International/1999 GMC K2500 Suburban (7400 VORTEC/4.10
Differentials)
1978 Argosy Minuet 6.0 Metre/1975 Cadillac Eldorado Convertible (8.2 Liter
V8/2.70 Final Drive)