Twenty Ten Header Image modification

I am using the Twenty Ten theme, and was wondering if anyone has recommendations on how I can do the two following things:

1. Link the Header Image to the full size image. I have tried doing this through the image info itself (description, etc), but it hasn’t helped. I’m guessing I will have to modify the theme..

2. When the cursor rolls over the Header Image, it displays the full image, as opposed to the cut down image. It would be similar to this (https://www.nsftools.com/tips/ImageResize.htm), except only 1/3 of the image would show at first, and then it would open up to the full size.

Any help is greatly appreciated!

Thanks