Here's a good place to look. ISMACS is a vintage/antique sewing machine group that has a ton of history about all the companies and machines.
http://www.ismacs.net
Here's another site that has a lot of info on the various Singer models.
http://www.sandman-collectibles.com/...r-machines.htm
So, read and read and read. Then come to the Vintage Sewing Machine Shop thread and ask questions. You'll get good information and answers!
Good luck. I was in your shoes not long ago, but have spent time educating myself, and have acquired the machines I really wanted after learning about them.