As for the class-by-race problem, I can think on 2 possibilities:
As a example, I'll take a Human Tyrr who has dual Iss Doomcrayer (Orc).
1) The person create a new character, orc-race, level 1, and the current char is "transfered" to this one, just like Name Change service (which would be even more viable, as you have this service already).
2) The person must have a dual class compatible to this char. The Human would be Iss Hierophant (which would requires Chaos Essence to change to Doomcrayer).
The first solution is my favorite.