Geek Piano Favorites

I've been thinking of recording piano versions of some songs you might not expect to hear played on the piano. They mostly happen to be somewhat geeky songs, so that suggests the theme.

Here's the list so far:

• Birdhouse in Your Soul
• Ana Ng
• Dr. Who Theme
• Crazy Loop
• Still Alive

Copyright

Not sure how the copyright thing works on this -- if I give away my recordings of these songs, am I still supposed to pay the copyright holders, and if so how much? How about if I want to sell them?