>> So after changing the battery I may need to adjust BIOS settings, such as Time & Date is it?
If the old battery is very low, or some time elapses between removing the old one and putting the new one in, the BIOS settings may be lost altogether. If this happens, you'll probably get a message when you boot, saying that you have to go into the BIOS setup. It will then be set to its defaults, and you'll need to set the time and date, but probably nothing else.