First, the live-in roommate: Typically, you should see the language " no members of the opposite sex that are not related by blood or marriage shall stay overnight." But with your order it sounds you must prove a relationship; however, I can tell that at least where I practice Judges do not like the live in roommate. So you may have sufficient change in circumstance to warrant taking this back to court to amend custody/visitation.
Second, First refusal: This presumes cooperation of both parents. So when you take him to Court to change the order due to the girlfriend, make sure language is in the order demanding his work schedule so you can actually have the "right of first refusal"
I believe you need to consider filing a motion to amend the previous order.