Helper Applications & Finder Icon

[thisbechuck]

Two questions... How can I change which applications are opened for .mp3, .html, .jpg files from the OS X finder?

How can I change the icon of "Finder" in the dock?

 

[slur]

1. Get Info on an MP3 file (for example)
2. Select "Open With Application" from the popup menu
3. Select an application from the list or "Other..."
4. Click the "Change All..." button.