The AI often gets distracted by fighting the hero along the way and sometimes doesn't have enough movement points to capture the castle. Stupid AI! :)
Often, but not always! At higher difficulty levels, the AI often prioritizes the castle over the heroes.
And stop using red, bold font! What is this, kindergarten!
:) Maybe, although it would be better to use bold, in my opinion.
The morale of the units will be neutral (unless there are buffs, artifacts, and Angels in the army). The second race in the army gives a minus one to morale, regardless of the number of units - only the number of races matters. I think it was like that before...
I almost didn't write my interpretation correctly, but the meaning is still clear. :) And you are absolutely right here.