Dreamweaver is absolutely nothing like iWeb. If you're not serious about web site design, you'll find it a waste of your time to even try to use it. It's very powerful, but also complicated.
Yes and no. Yes in that it has WYSIWYG interface (as well as a code view). No in that iWeb outputs HTML, but doesn't work in HTML. The only way I really find them comparable though is that they both give you a web site.