It's hard to buy a RV out of Indiana these days that does not have at least some Lippert components.
I think the theory of setup on this thing is to set your head angle so that you have desired WD with the d-rings nearly flush with the bottom of the ratchet bracket.
I would think that releasing the tension would be a matter of just backing it off a click or two at a time on the ratchet stops.
As to the durability of the straps, I am going to go out on a limb here and say it will be largely down to the initial quality of the strap material. These kinds of straps are common in the trucking industry. I have about a dozen ratchet straps we use regularly for securing stuff on the equipment trailer, and some are multiple years old, with a fair bit of use, and they are hanging in there fine. I wish I would have been the guy that thought up and patented ratchet straps......these things work well.