Hello,
2) Where did you get that code? From MailChimp authors? Then you need to ask them in what place should it be added to work in right way.
3) To change the global breadcrumbs image go to Theme Options > General > Breadcrumbs > change the breadcrumbs image. To change the image on some page only use page featured image to change it.
4) Could you provide me screenshot for better understanding, please?
5) Go to Appearance > Menus and check what page or custom link have you added to your menu with label Home, looks like it’s not the real home page but some other page.
6. If you don’t like some elements you may remove them and add the other elements that suit your needs.
Regards