Any good quality hand lotion is what I find works best - the higher lanolin content seems to form a better and longer lasting barrier layer compared to moisturisers.
Apply the smallest quantity you can get away with and leave for a few mins to settle into your skin before spraying the mones. I manage to cover my four typical A314 points with a drop about the size of a pea.
You can apply over the mones as well but that seems to be a tactic for the very hottest/tropical conditions where you are looking to massively reduce diffusion. Anywhere else it would probably stifle diffusion altogether.
I don’t know that one at all. Personally I’d go for a straightforward hand lotion rather than a “technical” product as there is less potential risk a more esoteric ingredient interacting negatively with the pheros.