As for the suspension of the tarp first...I don't see why not. The button hole straps are wrapped around the tree first and the tarp connects to them anyway, so absolutely the tarp could be pitched first. Just may have to go back and re-tension again after hammock is up.
No provisons for shock cords to ground from hammock. My understanding of the shock cord on the Warbonnet is that it really is there to expand the shelf area and move some of the loose material on the opposite side away from the hanger. I suppose an added benefit is the reduction or lessening of swinging.
I did not notice any tree damage from the straps, although my first impression was that the rope was a bit narrow. It worked well and didn't leave marks that I saw.
Thanks for watching the videos.