Assuming the footer and header are the same on all pages, I would use a base controller for that, that extends Controller_Template
So you'll get
class Controller_Base extends Controller_Template {}
And
class Controller_Auth extends Controller_Base {}
your base controller will setup the template, deal with header and footer and all other code that repeats, and keep your Controller_Auth clean and tidy.
Oh, and remove all those use statements. NEVER use classes from \Fuel\Core !
All Fuel classes are aliased to the global namespace, which is part of the way Fuel extensions work. If you reference the core class directly, you bypass extensions, which make cause your app to break. Some packages no longer work properly, also, all core classes load other core classes from the global namespace, so you might end up with two distinct copies of the same class active.
So when you use Fuel classes, you need to load the from the global namespace, either by prefixing them with a \:
Fuel's filesystem is "cascading". It will search the local scope first (in this case the module), and if not found, it will fall back (to app in this case).
You can not specify you want to load from the app, if you want that you have to make sure there is no view name collision.
We solve that by using reserved "prefixes", for example all "templates/..." and "global/..." views are only defined in the app, and not in any module.