Hint for 2.2, #12: Refer to problem 33 from Section 1.6. (This was part of homework 3.)
Hint for 2.2, #16: Start with a basis {u1, ... , un} for N(T) (where n = nullity(T)), and extend this to a basis {u1, ... , un, v1, ... , vr} for V (where r = rank(T)). Show that {T(v1), ... , T(vr)} is linearly independent, and extend this to a basis for W. Be careful to order the two bases appropriately in order to make the resulting matrix diagonal. (Note that most of this hint follows the proof of the Dimension Theorem exactly.)