From reading the second paragraph of the problem, it seems to me that your answer is not correct for part 2b. My reading was that a 2^n rotate would take 5 blits of 2^(n-1). If this is correct, then your equation should be
B(2^n) = 5 * B(2^(n-1)) = 25 * B(2^(n-2)) = ... = 5^n * B(1)
Where B(x) is the number of blits for x. (Sorry for not knowing how to do fancy equations.)
For 2d, I read it as saying what is the time complexity of B(2^n). Give it a try and let's see what comes out of it.
Let me know what you think.