Hi Audie,
Glad you had a successful first flight even though it was a short one! I remember mine, I was so nervous! Like you, I had practiced on a sim (RealFlight G3) quite a bit with the Nexstar which was also my trainer.

A lot of similarities but I found that my engine was more powerful than the one on the sim. It was so fast it scared the heck out of me so I flew around 1/4 throttle to half for a long time during my training.

Do you have all of the attachments on the nexstar? Leading edge wing droops? Speed Flaps? I am asking because I never put them on my plane and it has always been able to do rolls and loops without problem. The roll rate IS very slow on that plane so you have to take it up high, full throttle at a 45 degree angle then roll. You can do better rolls later when you learn to use the elevator during the roll to pitch the nose up for now you need the 45 degree angle to keep it from dropping out of the sky.

As for climbing in turns, did it climb with the instructor or just you? Elevator usage on the can be touchy when learning and you have to really learn the right combination of aileron and elevator. A slight bank with a good bit of elevator is going to pull you through the turn into a climb and if you don't release the elevator soon enough it will climb even more. I had a problem with that, I was holding too much elevator as I came out of the turn which ended up in a climb.