Hi, we've been looking at antimatter for a very long time, it was experimentally discovered by Carl D. Anderson in 1932 when he saw anti-electrons :) The wikipedia post on antimatter is actually very good so take a look there.

I like the Dan Brown books as well, but it is important to remember that they're fiction.... (!)

Extraterrestrial life probably exists in some form, considering how many planets there are. But then, lichen, amoebas etc are also life, life does not have to mean little green men in flying saucers. Now why we have not seen it (or they us?) is a completely different question, and more of a philosophy than a physics question. Google Fermi paradox if you want to read that philosophical discussion :)