I agree with the upgrade arrows. They makes it harder to notice which buildings needs an upgrade or not. (We now need to look at the building level in the list instead of noticing instantly which building can be upgraded or not.)

For the mercenaries bug, I didn't experienced it myself, but a friend on Siege of Acre was unable to accept barbarians when he should have been able to. It looks like the limit for Almogavars and Berserk also accidently applies to some other type of mercenaries.