I don't know too much about them either. What I do know is that they are kind of like chalk, but softer. I have the earthtones set at the bottom of this page.http://www.artstuff.net/alphacolor_pastels.htm
As far as using them, I have heard of using sand paper and sanding the stick to make a fine dust and then applying it with a brush. Another method I have heard is using a knife blade to scrape the side of the stick and collecting the dust (and then applying it the same way, of course). You may have heard this before, but when you get done and you like the results, spray the model with a clear coat to seal in the dust. Other wise it will get brushed off when you touch it. This is nice because if you don't like the way it looks, you can brush it off and start over. Also, you should apply it a little heavier than you think it should be; I hear it looks a little bit lighter after you spray it with a clear coat. I like the effect too. I will be approaching the weathering phase of my B-24 soon, then I'll try them out. Until then, good luck!