Well I have to say that a week ago We (wife and I) were in the same boat as you with a new to us 1959
Caravanner that my Wife inherrited from her fathers estate. I found this site after typing "Airstream" into www.Google.com.
I came in here with a barage of questions and in one week these great folks answered all my questions. Extremely knowledgable group of Airstream folks here.
Look through the site and there is a wealth of information already on hand. If you don't find an answer to a simular question then post up and more than likly you will get an answer your looking for within a couple hours (sometimes minutes) from sombody that has already went through the same problem with their unit.
If yours is like ours your probably going to find some floor problems. One of the most helpfull things I did was go through the section on interrior restoration and the sub forum of floor repair. I found the masive amount of photos that williamhenchel (sp) took to document when he did the "full monty" body off frame floor repair on his A/S very helpful in understanding the construction of these campers.
If you do decide to part ways with the original Fridge please let me know. I am one of the unfortunate ones that our camper was pretty well converted to a "Park" model that depends 100% on outside hook up to function. Both my Fridge and water heater were swapped for 110V units. I'm looking for a used two or three way to get mine back to self suficient. After reading and exchanging posts with these folks I have found these ald units are pretty hearty and as long as they are still holing their amonia charge they are usualy easily fixed. Only two things that generaly cause them to fail and thats a bad 110v heating element or a proably with burner or control valve for the propane.
Another site I enjoyed was www.vintageairstream.com
They have some good restoration tips and a outstanding photo archive dating back to the beginning of just about every model ever made and every year.
As for your water system. I'm not sure what you have. there were three styles used. One was a Air over water (Air presure in the water tank) On demand pump, and hand pump (yours would not have hand pump). Yours may be new enough to be On demand electric pump. If yours is still Air over water then drop me a line and I can send you a copy of my 59 instructions that should still be valid for your newer unit. If you want them right away. I'll be scanning these and putting them in my photo gallery eventually.