QI discard a Trail of Light during my end phase because I have too many cards in my hand, causing me to draw a card because of its ability. Then, I must discard due to hand size again. How many times does this follower's automatic ability trigger?

AIt triggers 2 times. When you discard Trail of Light, its ability and this follower's automatic ability both trigger and become pending at the same time, and are resolved at the next Confirmation Timing. Then since your hand would be over the hand size limit, you would have to discard again, which would trigger this follower's automatic ability an additional time.

QIf I discard 2 or more cards during my end phase because I have too many cards in my hand, how many times does this follower's automatic ability trigger?

AIt triggers 1 time. Cards discarded during the end phase due to hand size are discarded simultaneously.

QIf I discard 2 or more cards at the same time during my turn, how many times does this follower's automatic ability trigger?

AIt triggers 1 time.