Quote Originally Posted by Jambo
One rule I like using regarding retraining units is to always press "m" first to merge the units. If units are all fairly well damaged then this reduces the number of possible units to insta-retrain.
I agree. Just merge your units first and then retrain your fully populated units for their upgrades. I don't see this issue as a problem.

Quote Originally Posted by Jambo
I don't like the destroying of buildings idea. Not only does it reward you with plenty of denari, but it also means that if the AI were ever to retake the settlement then you'd be facing multitudes of peasant and militia AI armies.
I don't know about "plenty of denarii", you get a few pennies for them is all. In order to overcome your other objection, all you need to do is keep the old buildings until you're ready to pay for the replacement. Then destroy the old building and replace it with one of yours in the same turn. Problem solved.