A positive charge placed in an electric field will tend to move in the direction of the electric field lines and a negative charge will tend to move opposite to the direction of the electric field lines.
One way to remember this is that there is one velocity, and so the thumb represents it. There are many field lines, and so the fingers represent them. The force is in the direction you would push with your palm. The force on a negative charge is in exactly the opposite direction to that on a positive charge.
I will say that the the potential energy will be at its maximum.
Explanation:
potential energy deals with gravity and gravity deals with height, so when a object is in its maximum height it will have the maximum potential energy.
