If you haven't already read at least one comprehensive guide to gear and technique, here are a few to consider. I don't always agree with everything they have to say, and they lack a little bit when it comes to ultralight, but they're good introductory books.

The Boy Scout Fieldbook really isn't too horrible, though I get the impression that the author thinks ultralight is something you use to cut down on your electric bill. You'll have to read several different chapters to get the information you need, but it's a pleasant way to spend a cold, snowy Sunday afternoon.

These two are significantly better. Both are pretty quick reads, with solid basic information (such as, what's the difference between synthetic and down bags, what's the difference between a filter and a purifier, etc.) :

1. Hiking and Backpacking (A Trailside Guide), by Karen Berger: mostly "traditional" technique, but the information on gear basics is informative. Karen has a good writing style; you might also enjoy her book, Hiking Light Handbook, which deals with "mainstream" ultralighting (as opposed to "bleeding edge" ultralight.)

2. Hiking and Backpacking: Essential Skills, Equipment, and Safety, by Victoria Logue. Another good basic text, mostly on "traditional" technique. A little longer than Berger, but still not overly thick.

Now, if you really want to know about the nuts and bolts (and stitches, and foams, and fabrics) of backpacking, and are willing to plow through 500 - 800 pages, try The Complete Walker IV (Colin Fletcher & Chip Rawlins) or The Backpacker's Handbook (Chris Townsend.) These two books are classics. Both treat "mainstream" ultralight pretty thoroughly, as part of the whole spectrum of backpacking technique. Both are about as exhaustive as anything you'll find when it comes to talking about fabrics, materials, and construction of backpacking gear and how to use it in a variety of conditions. At some point, you really should read one or both - but it may be overkill for just getting started.

I hope I haven't misread your skill level here; if you've already read some or all of these, that's great. I certainly don't intend to discourage you from asking your questions, but it does seem like most of them would be more appropriately placed in the Beginner's section right now.