Don't worry so much about stuff. Two sets is fine, unless you start to have trouble sleeping and you feel like you are getting a cold - then you might be overworking it, but I doubt two sets is going to kill you.
Doing your 5 RM for a few weeks isn't going to harm you either. At the point of your 5 RM, you won't have to worry about RBE for quite a while. Besides, you'll likely gain strength and find that you can increase the weight after a few workouts, since your 5 RM will go up.