Raja_Rakshasa, if you're talking about the 2nd mission, don't end your turn near the shore. Then the enemy won't land after 7 days. You'll have time to build your castle. And if you have a fully upgraded Godrick (like I do), you shouldn't have any problems with the pirates.

Shambler, if you have version 1.0, I can't help you, because I haven't played that version. In the patched game, there shouldn't be any problems, because in some patch, Gilraen was weakened.

VANDAL, Markel resurrected Nicholas, but Nicholas became a Greater Vampire. There's a cutscene at the end of the 4th campaign. In the 5th campaign, Faidaen finally killed him.

Delta, you need to go to the surface and defeat the rebel near the Knight's Castle. There's a second exit to the surface there.

Stucker, find the Archdevils and defeat them. After them, there will be a hero. If you don't defeat all the demons, there won't be a hero. The demons don't have a castle in this mission.