One simply do-it-yourself fix in the .xml files for the animations is to pick a sub-pose you think is appropriate for an orgasm pose and change the values in the first field of <faceanimation> to 1 or 2 instead of 0.
This just puts the girl's mouth in the 'open' position, for 1 it's fully open (it's the position from Blowjob) or for 2 it's half-open, but it makes quite a difference visually! (example screenshot attached)
For the whole 'stop after orgasm' idea, one solution could be an extra sub-pose for each position that is 'stopped' - so the characters are in the same position (from behind, on the table, whatever) but the guy is withdrawn and not thrusting, just kinda taking a break, either for post-orgasm or just whenever.
Could also be extended to bespoke orgasm animations for each position too, although I tend to just pick an appropriate sub-pose (legs wrapped around in missionary for example) and perhaps tweak the xml as above so the girl's mouth is open!
A 'back to default pose' button could be useful-ish, I can't see myself using it much, but also wouldn't be too much work?