I have done a) yes it is (checking that u1.u2, u2.u3 and u1.u3 = 0 & b) by creating an augmented matrix and reducing it to RREF, giving me a coordinate vector.
But what is C asking? I have a feeling this assignment was used last year, but I know that they modified the curriculum this year, and it's not in any of the material (at least, not this notation). It looks like it is asking me to create a new Matrix, consisting of three vectors divided by their length. But I'm not sure. I've been through all the material and cannot find any examples of this? Any help?