For part (i), are you familiar with the parallel axis theorem? As to part (ii), a circular hole in a circular disk can be treated as the disk without the hole plus a disk corresponding to the hole with negative mass equal to the subtracted mass of the hole. You should also be familiar with the physical pendulum.
--Kevin C.
Where are you getting an from? The moment of inertial of the main disc is
and the "moment of inertia" of the hole is
where is the density of the material.
So
To find the period for small oscillations use
where is the distance from the center of mass to the axis of rotation. I leave it to you to find .
-Dan