Labyrinths of the Mind

I've almost completed the map, defeated the mages, but I still don't understand where the Dwarf Castle is and how to get to it. Several questions arose during the game: 1) Quest for magic books: Was it intended that the main hero's mission fails upon completing the quest, but a secondary hero gains +3 levels upon completion? 2) The tower that increases stats doesn't work correctly: when you enter it again, it doubles the current stats and doesn't apply the effect for only a week, but permanently (I got +1 to defense once and +5 to attack five times), so I stacked over 1000 attack.