Greetings ,
I understand what you are talking about, and you are correct. I'm not a scripter but for the part where you would move a little, is possibly simple.
Youre script of course would need to be
1. time/unit pos based
2. Either using the random in script for how long fatigue simulation would take or just time in that pos. Now big thing to remember is that no one has the exact stamina in anything. Some may be able to hold an up firing pos for 5-10 minutes (doubtful but not impossible) and still be somewhat accurate. Others 1-2 minutes. That is why snipers pull off their best shots in the prone pos.
For the movement, when wounded in OFP, your aim goes from bad with a slight wound to almost bouncing when seriously wounded.
For AA, I'm not sure since when I usually get shot it seems that the AI has an almost perfect kill ratio (I would say this rather unrealistic, less you are against Special forces, with these fellows their weapons become an extension of their bodies.
Hope I helped, even if a little, and hopefully someone will offer to write you a decent lil script.
Happy Holidays