Customize image in header

Hi,

I don’t like wordpress’s default display of featured images on pages and posts, so I really wanted to try out yours!
It would look great if I could edit the way it is displayed, although I couldn’t find where it is displayed in the code.
– I noticed you display a subtle black overlay over the image on the header: i would like to extend it over the whole image to 60% opacity
– Could I disable this image in header for certain pages? (tag, category, link) I still don’t want the default wordpress display, but sometimes my feature images don’t fit this format.
– I couldn’t find in the documentation where I can see all of the attributes for the header, so I can edit some details with CSS

If you can help me with that, this would definitely be the best theme I’ve used so far.
Thanks in advance!