A roller coaster is a good example for a place to find both kinetic and potential energy. Before a drop, it has potential energy. At the end of a drop, it has kinetic energy. Half way through the drop, it has kinetic and potential energy at the same time.

potential. And then when you drop it, it becomes kinetic.

No.

There is no difference between potential difference and potential drop. Both terms refer to the difference in voltage (i.e. potential) across a component. Depending on how you look at it, both terms can refer to positive or negative differences, i.e. drop, for instance, can be negative, implying a rise.

Yes. If you drop them, the potential energy will convert to kinetic energy.