For comfort, sure. I'm just not sure if it's long enough to have an optimal width. Personally I wear a hoodie and put neoprene knee sleaves on my elbows, dos the job.
It's not ideal. The main purpose of the Zercher(for me) is to strengthen the upper back. I prefer to only use the weight you can lift with the arms more upright. You will build up the strength over time.
Yes. It's like a front squat.
With a wide stance break at the hips first, pushing the knees out.