Regarding the Scouts - I'm guessing there's a "+1 Observation Range" upgrade they can get. I'd hazard to further guess it means they're vets at observation and perform better recon without being spotted...? Who knows. I usually choose the HP/healing upgrades for them anyway.
Another thing that always pissed me off about the AI is them offering a trade, which I accept, and then they say "that's not nearly enough of a fair deal" or some other rejection message. You're the idiot that came to me to offer a trade, bub...what the hell.