Modding

AndyUK,
2. The probabilities of skill drops are defined in the data.pak/GameMechanics/RefTables/HeroClass.xdb file. Find the section with the desired race ID and look for the lines in AttributeProbs.
3. In the hero file (AdvMapHeroShared, place the hero on the map, and look in the properties for the path to the file in the Shared field), you can set the desired skill in the Editable/Skills or Perks field. If you're talking about the skill wheel, you need to find both skills in GameMechanics/RefTables/Skill.xdb and swap their IDs (this will swap the skills).
4. In the advanced map editor (instructions in the map-making section), find the AdvMapDesc table, and through it, the desired mission (in the Maps/Scenario/MissionNumber folders). Open the mission with a double click, select the desired city on the map, and press the spacebar - this will open the properties window. From there, it should be obvious.
5. Creature levels can be quickly changed in the advanced map editor in the Creature table. In the properties, look for the CreatureTier line. Then, in the TownBuildingSharedStats table (in the data.pak/GameMechanics/TownBuildingSharedStats/RaceName folders), select the corresponding dwelling file for both creatures being modified and swap the IDs in the Creature lines, or simply swap the contents of the files.