replace site title with logo above header image

Hi! Thanks a lot for a great theme! I have a few questions about custimzation, and would be very grateful if you could help with these? If you need to take a look at the site please tell me since it has a "under construction" plugin now, and I have to unlock it! First I'd like to add a logo above the header image exactly where the site title is now. How can I do this? I'd also like to make the header image the same full witdth. Finally I wonder if its possible to custumize exact html-colour on the menu?