Hope this isn't a dumb question, but how does Philae stay put? If the gravity strong enough to keep it on the surface? Also, as the comet nears the sun and parts of the comet start flying off, is there a threat of Philae getting swept along with it?
To add to what everyone else mentioned: Philae's science mission is slated to last for 2.5 days - the batteries have ~65 hours of charge, that's it. The hope is that they may be able to charge it and keep gathering data afterwards.
So it's not going to last nearly that long.