That's a very broad question you ask. I guess the easiest answer is that 45 year old cars of any brand are very different from contemporary cars even though they may still appear stylish.
Your location simply says "Northwest" so I am assuming you live somewhere in the Pacific Northwest. If that is true, I suggest you visit:
www.birdbrains.net
This is a dealer in the Portland area who maintains a modest size inventory of baby birds. He is very knowledgeable about the cars and is just a genuinely great guy who will share his knowledge with you if you visit his facility. He is also as honest as you coul ever hope to find. You could confidently buy a car from him at a very reasonable price and he could probably tell you more about it than the previous owner.
To answer your specific question about rust, I offer the following tid-bit. In addition to the common rust spots in the floor, rocker panels, and quarters, the '55 & '56 trunk lid is susceptible to rusting in the lower trailing corners. Of course, there is such a thing as no rust at all! --anywhere.
If you have questions that are Bird specific, post them. We'll try to answer.
Tom