The idea was right, there was a slip of arithmetic. The distance the container is raised is $$\frac{\frac{5\pi}{6}}{2\pi}\times 12\pi.$$ This is $5\pi$.
For the second problem, the idea is much the same. Let $\theta$ be the angle of rotation. Then by the reasoning of the first problem, we have $$\frac{\theta}{2\pi}\times 12\pi=24.$$ We want to solve for $\theta$.