is this website developed using dreamweaver?

Pretty sure it was built with Dreamweaver. The way you can tell is how awsome fast it is when you have to go through a few hundred threads to find the help you probably needed before you lost your mind and asked this question?

It's possible, but if it were, they used very little of DW's built in functionality. 

It looks like a fairly clear case of copy and paste development to me.

If you're asking the question to determine whether or not the site could be brought into DW and modified, it could. DW doesn't make proprietary "dreamweaver html pages" it's a glorified text editor, you can work with just about any code built in just about any editor in DW.