No answers to your first question. Second question- I did not like the hinged beam, fold up/down leg and fold out of the way against wall. I wanted a solid beam with no shake or wobble.
Here's what I made...
I built a small table with beam mounted flat. End fits at my stomach height. Can be rigged for a work bench as well.
No bending over or reaching up to flesh downward... very solid and comfortable working this way.
I can remove beam in the off season.
I did add a two blocks to hold fur board so I have both hands free while pinning pelt.