A:AnswerOf course this is going to depend on how much you use the phone, but we only have to charge ours once a week roughly, sometimes every 4-5 days.
A:AnswerYes you can and I had to do that on all the handsets. It cannot be just turned off on the base usnit, it has to be done on all the handsets. Its under the Menu option and go to Talking Caller ID and you can turn the feature off and again, this needs to be done all handsets.
A:AnswerThe keys are backlit when you pick up the phone to use it. At that point, you can see the keys in a completely dark room. After you put the phone back in the cradle, the keys stay lit for about 15 seconds, then go dark.
A:AnswerDon't know exact battery number but you can type in google question .. put phone type in and it will come up. It is 2 probably AA batteries bound together. Very easy to install.