Tom,
invest some enjoyable time in reading All of the stickys- from beginning to end.
There is no substitute for doing your "home work".
When I first came here, in addition to the stickys, I read all the posts in each forum, some go back years and run to the 100's.
Sounds strange, but that is the way I approach a new subject, and it gets one up to speed in about 3 months. There is just no substitute for time spent doing the grunt work. It does not all "make sense" at first, but gradually the pieces fall into place.
Much has been said about owning books, but you have pretty much torpedoed that suggestion for yourself. You really could/should consider the dvd of the Sturgess/Goertz book for about $40- even if you have to learn how to use a cd/dvd in your computer- most are capable today.
That DVD would get you a three volume 1800+ page reference book that will answer many questions for you, has great pictures, is engrossing in its detail and history. But it would not explain the "hot pin test", or use of a black light, and some other tricks of collectors.
The search feature of this forum is also a great resource. Many threads contain information about "sneak" lugers; which is a pretty much obsolete and old collector's term.