1. Basically, I just wanted something I could wind a length of wire around and stick in my window. The tube did the trick. After the show, I tried a few other things, like wrapping the tube with tinfoil, but the basic wire around the tube design performed best.

2. The shielding is there to keep signal interference out, which is useful if you have a clean source to start with (ie: Cable TV or a properly designed antenna). In my case, I just wanted to pick up as much signal as possible, and this is what I had to work with.