I can't imagine that 1 is a feature. What would be the point of that? The fortification is supposed to by the player some time to bring up reinforcements. Why allow the enemy to seige and attack in 1 turn?

I don't think 4 is a feature either. It would be better to take the enemy as they come up the ladders and therefore imediately surround them than to move out of their way and allow them up and allow more enemy up behind them.