I like most of those ideas, if not all of them.
I mean, I always felt enemies acted too much in a suicidal way. When you see your opponent is DEFINITELY superior, logic says that you'll try to get out of the fight: run, cast invisibility, beg for mercy, anything but keep on fighting and be killed.
However, the fact that fleeing enemies can be annoying, gameplay wise, it's true.
Don't know... maybe those should be short-timed, strategic retreats. Run to call your buddies, or to heal yourself...
If they really want to end the fight, instead, they should give up: you get the chance of taking whatever they have, and they are converted to non-aggressive.
Could be a lot of work to make it work under the vast number of possible situations, though...
These things should take into account the NPC's personality (coward, bold, aggressive, timid, etc.) and the exact situations: were they the ones who attacked you or was it you that attacked them?
Let's say you enter an house, beat the owner until she surrenders and take all of her stuff as a consequence: maybe she will not attack you anymore, but it would make sense if she reports you to the guards at the first opportunity! ...but then, you may have intimidated her into not telling anyone or you'll be back... Which in turn would make Speechcraft more useful... mmm!