2c. how much daylight would there be on dec 21 in the northern polar regions?

None, it would be 24 hours of darkness

Explanation:

This is because December 21st marks the astronomical start of winter for the northern hemisphere with the winter solstice. During this season the days are shorter than the nights, and as we get closer to the North Pole, we will have up to 24 hours of darkness.

That is why on December 21st, the sun is not visible for 24 hours and the next days (the closer it is to the north pole) it will stay that way. Therefore, the inhabitants of this area will have longer periods of darkness.

not completely sure but i think it’s many moons, smaller in size and a ring system.