It's not a good habit to get into. I got into the habit of using both brakes and had to panic stop. I jammed both brakes on and the rear started to skid so I lifted both brakes. Needless to say that's not the quickest way to stop, especially when your front tire is pointed at the side of a car.

There is no difference in noise output between front and rear brakes. If it's noisy adjust it yourself or take it to a bike shop. I used to like having a noisy rear brake when I rode my hybrid so I could use it to "alert" pedestrians I was overtaking them without getting that confused or annoyed look.