fusible webbing

[samaravachss.livejournal.com]

So I have been playing a lot with fabric crafts and am a little confused about all of the different types of fusible webbing. How does it work, exactly, and how do I know what kind to buy?

Mostly, I want to be able to do two things: applique, and stiffen stuff (like for the bottom of a purse?).

For the applique, can I really just cut out a shape of fabric, fuse it to the webbing, then fuse that to something else? Does it not fray?

Thanks for any help.