First of all: Very nice puzzle! I liked it a lot because it was challenging and fun.
I have two problems with question number tree:

1. There are two many possibilities. You could say Mary is the odd one because she is a girl and you could also say John is the odd one cuz he doesn't have an "a" in his name.
2. My bigger problem is that it is impossible to solve that question if you don't know Supernatural and you don't want to google the names.

My solution to Q2 A was 0. Looking back your solution makes much more sence but I want to share my logic with you.