1) Are you using a child theme? If not, I highly suggest you read about them and create one. 🙂
2) Are you trying to move the entire footer information to the top or just the entry-meta that says: “posted in…” ’cause if that is the case you can just move the template tag: twentytwelve_entry_meta() to the section you want in your header.
3) If you are wanting to only display on blog posting you can add a PHP conditional around the .entry-meta. Something simple like:
if ( ! is_singular() ) {
// entry-meta things you only want displayed on blog posting
}
Hope that helps you a bit.
Solved!
Moving the twentytwelve_entry_meta to a new place solved both my problems.
Thanks for the help, and if anybody would like me to go into more detail about how I got it to work, just say the word!