number 1, the walls are needed for me, if you like cheats (if you dont your noob) the you can just get a few bandits and put them to mercenary then hired blade, they are the best unit and dont die easy! i got 75 like i said earlier. number 2, you havnt killed them all
ive found this problem but if you hold ctrl and press f4 then that last guy (who i think is on a roof) will die and you can go back

hope this solves it