1. Why is it Choshuv?
Presumably because, if your shul is oriented correctly, it’s the front of the shul. Which is why I generally make it my business to sit in the last row of any given shul if possible.
2. Who qualifies?
That would probably be at the discretion of whomever assigns seating in said shul
3. Which side of the Aron Kodesh is more Choshuv?
I wasn’t aware that one side was more chashuv than the other. I’ve been at shuls where the Rav sits to the right of the Aron and other shul where he sits to the left. Ask your LOR.
The Wolf