Very impressive, really makes me wish there was dialogs or something to go with these. The only thing that bugs me if the sfx seem to be backwards, pulling all the way out will make the contact sound and once you notice it you cant stop noticing it
BTW I found that the extramodcore (as of 1-5-1) is what makes the human legs not go away so make sure you do have that for this specific mod to any one reading this
Regarding the issue with the arm placement:
The cupping/holding breasts positions are a feature of animtools.
I'm not sure how this is implemented. Possibly the hands are placed relative to the breast mod's origin point so that the hand matches the position of the vanilla breast artwork? This of course won't fit the modified natural breast's shapes.
I don't think that I can do to fix this in the scope of the natural breasts mod alone.
Having an (invisible) symbol which designates the hand placement point, which is then used by animtools might be a strategy for adding compatibility for the hand positions.