Wow!! Unlocking the camera zoom from the developer panel works great!! Maybe such degree of unlocking isn't desirable for normal use, but, after trying it, I strongly feel that more levels of zooming out should be allowed in the default behavior.
Regarding units selection confusion, yes, I was using select box, but I find it difficult to see where are the units that can work, the units that can fight, and the units that can heal. I don't recall feeling this difficulty when playing AOE, I clearly figured out where was each unit type. But it was many years ago, so maybe my memories aren't accurate. Maybe one reason is the hybrid civilian-military units, which, even historically accurate, make gameplay less clear IMHO.
Anyway, I feel that it would be highly desirable to study new ways for achieving an addictive gameplay in single player mode. AOE made you desire to start a new game when the previous one ended, and I still don't have this same feeling with 0AD (don't take me wrong, I love it, but I find myself enjoying looking at the buildings, the animations, and testing things rather than enjoying playing, which might be just a consequence that the game isn't finished, but could also be a symptom showing that addictive gameplay needs more study).
Other minor aspects that maybe could be improved are corrals (if I'm understanding it correctly, you need to manually kill the animals, but it would be more convenient to have some workers doing the farm work automatically).
And definitely, a more accurate depiction of each civilization religion in their temples/healers/monks/priests, etc... will add a more realistic feeling. Different healers could have different powers and habilities. Some temples could have (historically-based) additional uses (for example a monastery can have a very important library that helps make discoveries, or a liquor distillery, and there can be also civilizations whose healers are hermits who try to be alone, a distance from populated areas, and who would automatically walk away from populated areas (just a bit, perhaps, because otherwise getting to them for healing would be too difficult). Just quick ideas, but very cool stuff can be done with a more accurate depiction of the religion from each civilization.