Q1. What is your definition of cheating?
A1: Physical contact, or sharing time with this other person that you should be sharing with your mate.
Q2. What is the difference between a wifey type chick and a jumpoff?
A1: I hate the word wifey

, but to answer your question.
Wifey - brings more than just sex, you are able to have deep conversations, you would have your family and friends meet her and not feel embarrassed, and you hit her up to spend time and not just f*ck
Jumpoff - usually called upon in the late night hours

, don't stay on the phone for more than an hour, don't have an interest hanging out with this person and would kick her out if shes not offering sex.