Mostly covered by... (if more than one - continent with biggest bonus)
not really, if you would script it exactly like you stated above, it will most likely give errors, since you do not state exactly what will happen if there are continents, but none of them is the biggest, will cause the script to malfunction or not function correctly
anyways like has been said before, it doesn't matter a lot since it would be better if the zombies would first check which territory has the most armies and then
check which one of them gives the highest bonus, if any., then the coding will be like this:
if 'number of armies >=4' attack 'highest territory adjacent to it'
if 2 or more territories are equal(only count the highest) 'attack the one which creates the highest bonus' (potential food capacity) (or most territories inside a continent, for example..)
if equal(and highest, of course), start attacking alphabetically