Will a firmware update erase my personal data?
Do a backup of your phone's important files, don't risk it, if the phone reinitialises it isually resets it to its factory version, erasing all the data. Also your apps are very likely saved in a list so that you can reinstall them after the reset, so don't worry about them. Use google drlive or some other service, take the SD card out, and do the firmware update, if you want. Just don't risk it.