add a button in header

Hi,
I need a few customizations to the header in Fortuna theme.
1. in settings it seems like the maximum height is 150px. Can you give some code to increase this. the logo needs to be enlarged and header does not automatically resize to accommodate.
2. Is it possible to add a “Donate Now” button in header linking out to payment platform?
3. With the addition of the extra height and button, nav. menu should be lowered.

See screenshot here http://imgur.com/a/NT3s8

Thank you!
Nancy