1. What is the pointed part of a cone called?
The top point of a cone is called the vertex.
2. Is the vertex of a cone always directly above the centre of the base?
Not necessarily!
If it is, the cone is called a right cone.
We usually assume a cone is a right cone unless told otherwise.
3. How can you find the slant height of a cone?
If you are given the radius of the base and the height of the cone, you can use trigonometry / Pythagoras' Theorem to find the slant height.