As of right now me and my friend workout together and this is our schedule:

Day 1 - Chest and Triceps
Day 2 - Biceps and Back
Day 3 - Shoulders and Forearms then about 7 hours later at night we do our legs.

After this we take 2 days off to rest and then start it again. My friend asked his fitness teacher about if we got enough rest and he said we have way too much rest and should either only take one day off, or work out 5 days in a row then take a day or two off. From what I have heard two days is a pretty good amount of rest and only taking one day off could lead to overtraining. Would taking only 1 day off be better than taking 2 days off? I have no problem with only taking one day off if it's not overtraining.

I would suggest doing all your upper body one day, then lower body the next, then one day rest. Repeat.
Thats usually what I do, but I also pay close attention to how Im feeling. If your not getting a little tiny bit sore from working out an your resting 2 days, then your resting too much. You should only be resting if your too sore to workout, optimally you want like 36-40 hrs of rest after working peticular muscles. Unless your still sore, so a large part of the rest cycle seriously depends on how extreme your hitting your workouts. I had workouts at the gym where after I had finished and I had to wait 30mins to drive home because I couldnt control my arms yet.
Sometimes if you are a little sore a light work out will actually help relieve some soreness. Another general rule of thumb I use, if Im not getting a little sore after workouts then Im not working out hard enough because my body has adjusted to my current rountine so my routine needs to be altered.

The amount of rest you need is determined by the amount of volume and the amount of intensity you use in the workout combined with your dietary habits (food helps you recover) and your sleep habits ( at night is where recovery happens). Are you making strength gains every 2-3 weeks? If not something needs to be changed.