A heavenly body revolves around a massive star in a highly elliptical orbit..Is its angular momentum constant over the entire orbit?

A comet orbits the sun in a highly elliptical orbit. Does the comet have a constant:- linear speed,

A comet orbits the sun in a highly elliptical orbit. Does the comet have a constant:- angular momentum,

A comet orbits the sun in a highly elliptical orbit. Does the comet have a constant:- kinetic energy,

A comet orbits the sun in a highly elliptical orbit. Does the comet have a constant:- potential energy,

The orbital angular momentum of 3p electron is :

A comet orbits the sun in a highly elliptical orbit. Does the comet have a constant:- angular speed,

Answer the following :- Comets move around the sun in highly elliptical orbits. The gravitational force on the comet due to the sun is not normal to the comet’s velocity in general. Yet the work done by the gravitational force over every complete orbit of the comet is zero. Why ?

A comet orbits the sun in a highly elliptical orbit. Does the comet have a constant:- total energy throughout its orbit? Neglect any mass loss of the comet when it comes very close to the Sun.