Gears you can try to first practice playing with the rear and keeping the front in the middle or small depending how many cranks you have in the front. As you go up small hills, the steeper the hill the larger you want to go on the rear and as you level out or go down hill you can move to a small gear. Once you start getting familiar with the rear then you can add in the front.

Front brake has most stopping power and if wheel locks, you will flip forward. Rear slight stopping power and if wheel locks, it will just drag. Brake can be mostly front to slow down and both to come to a sudden stop.