[Jared at Pelican Parts]

I'd say it probably has to do with solar radiation...

As for why it flies backward, one guess would be that in order for the shuttle to re-enter the atomosphere, it needs to fire the two engines on the back opposing the direction of which it is travelling. This slows down the shuttle, the orbit decays and it slowly gets pulled down. They then simply flip it over onto it's belly and re-enter..

Those thermal tiles are really cool.. I saw a demonstration of one a few years ago where a guy heated one with a torch until it was glowing, and then picked it up with his bare hand.. Neat stuff...