Twenty Twelve: Remove header border, extend header

1) I’m using the Twenty Twelve theme. Using a custom header and I’d like to remove the default border. Is there a line of code I can remove/add from the style sheet?

2) Also, I’d like for the header width to extend bilaterally so that I can have the header graphic spill outside the main body and overlap the background; specifically I’m trying to have ribbons stick out from both sides of my custom header and I want them to be unconfined.

3) How can I separate the header from the main white body? I want my header and menus directly on top of a custom background and have the blog post body begin below the header with a bit of spacing.

Thanks so much! ??