Oh yes, I almost forgot to mention.... the adaptor is magnetic! this is not in the description... or at least I didn't see it!
However, it does not hold in the vertical position ;-)

Hello
Unfortunately I can't answer that because I haven't tried it.
The adhesive surface is in any case over the entire rear surface of the adaptor and is from 3M.
I bought an extra flat, smooth, non-porous cover for it (Google Pixel 7 Pro) and it works perfectly with it.
I've only had it for a short time but I've already tested it and it holds perfectly... it doesn't wobble around... Simply perfect!