No, you won't loose any settings. The power windows will have to be re-programmed as shown in the owners manual.
Under what conditions does the battery loose power? ie how often do you use the car ? Will the car start?
the radio might loose settings, but will not need a 'code' to make it work again. it is keyed to the vehicle 'vin'
resetting stations is trivial.
but as pegleg asks, why does the battery need replacing? if its just 2 years old this would be done under warranty