Trex Decking Questions, Please


Thinking of TREX for an outdoor (uncovered) Deck re-do.
They have a nice site, but still have a lot of questions.

Thought I'd ask you experts here:

a. General thoughts and comments regarding Trex ? Pros & cons, etc. ?

b. Exactly what is this "stuff" of Trex made of ?

c. Does it need to be stained also ?

d. 1" thickness adequate and typical for Deck ?

etc. ?

Much thanks,