As was mentioned, using rudder in the turn in a full scale airplane keeps the turn coordinated. This is of course true for models as well.

The reason rudder -in the same direction as aileron- is added is to counteract and correct for adverse yaw. Adverse yaw is the drag that is caused by the downgoing aileron in a bank/turn. The down aileron drag causes the nose to go in the opposite direction of the turn so adding rudder keeps the nose going where it should which is the same direction as the turn. Most full scale airplanes have differential ailerons to lessen adverse yaw; the down going aileron will not deflect as much as the opposite wing aileron goes up, and vice versa. Aerobatic airplanes have virtually no adverse yaw. They can do 'pure' rolls with almost no movement about the yaw axis. But they sacrafice other stability and handling qualitites for such pure flight, which isn't desirable in other more standard purpose aircraft.

Use up elevator to keep the nose up in turns. As any airplane banks, its load factor (G force experienced) increases. This means the plane gets heavier in a turn and needs more aft elevator to keep the nose up. At a bank angle of 40 degrees the load factor is 31% greater than 1 G level wings flight (1.31 load factor) and at 60 degree bank the load factor is 2.0 which means the plane is twice as heavy at that bank angle. The steeper the bank the more elevator one must use if altitude is to be maintained. But most of our model flying isn't that precise so its more a point of interest; but that is the reason you will find the nose dropping in banks, because the plane is experiencing higher G's which is weight. The more shallow the bank the less the nose will tend to drop.