Is it forbidden for my reflection to appear in the mirror while I am asleep? Is it obligatory to cover the mirror in this case? And what is the ruling on a husband having intercourse with his wife in front of a mirror?

There is no harm in sleeping in front of a mirror, as the image reflected in it does not prevent the entry of angels. It is permissible for a married couple to look at each other's entire body, whether during intercourse or otherwise. However, it is disliked for a person to look at their own 'awrah (private parts) without need, and looking in a mirror is like direct observation.