Nice little car! You may want to check out the Little Indians chapter of the Pontiac-Oakland club, it's specifically for owners of 1961-1963 Tempests and Lemans.
http://www.littleindians.com/
The first thing you should buy is a factory shop manual. They show up on eBay, from online vendors and at swap meets. I believe you can get a copy on CD-ROM as well. A couple sources include Walter Miller at
http://www.autolit.com/ and Bob Johnson at
http://www.autopaper.com/
Kanter Auto sells a lot of parts for brakes, suspension, etc.
http://www.kanter.com/
You can send a request to Automobile Archives at
http://www.automobilearchives.com/ and they'll email you a list of all the new old stock parts they have on hand for your car. They're good guys to deal with.
California Pontiac Restoration (CPR) is another good company, although I don't know if they carry much for the early Tempests.
http://www.pontiacparts.net/
East West Auto Parts in Tulsa has a lot of parts for early Tempests and Lemans, but I understand they're not particularly cheap...look in the archives to find out more.
http://www.eastwestautoparts.com/