Can the AI remount previously dismounted troops?

[hoplitis]

What about unarmed trasport helos, landing crafts etc?

As to the specifics of the subroutine... Boy, so many questions (How is the "conflict zone" defined, retreat towards the baseline or towards a direction of "fastest and secure retreat", can favorable terrain be exploited, are the 20 hexes enough taking the increased range of modern weapons and so on...). But again better to keep it simple.
Can the retreat distance (RD) be related with the time frame of the scenario? 20 hexes may be considered "safe" in the '50s, but in 2010? Maybe something simple as an RD per decade. But then you are introducing a variable in place of a constant......
Ok enough brain(?)storming.