Moo, did a Battle.NET search.
2) How do I allow heroes to gain experience from creeps past level 5?
From the main window, use Advanced->Gameplay Constants. Find the field called Hero XP Gained - Creep Reduction Table. Each number in this list corresponds to the percentage of experience the hero will gain from creeps at each level. To make heroes always gain full experience from creeps, set the list to have a single entry of "100".