tilesets is for melee creeps defining for which mapTerrainType (Felwood, dungeon, icecrown ...) they are allowed to be randomed, In world Editor for placing unit it defines in which mapTerrainTypes you can see it in the creep list.
abiltTest looks like it is the sum of stats (str, agi, int) gained per level.
Archimonde and Cenarius are OP. archimode has 10 and cenarius 9.6 a little bit weaker.