No books avauliable, but i'll try my best...
The brake adjuster unit keeps the same clearance between the pads and disk as the pad wears out. Out of the options you mentioned I'd choose...To maintain braking action.
By drooped nose, i'm assuming you're refering to the negative angle of attack some a/c have on landing. This is inbuilt into the a/c so as to increase the load on the wheels, thus allowing harder barking (similar effect to spoilers)
Hope this helps