Updating of firmware of APM 2.6 procedures

I have read through the wiki, and could not get information on what procedures to follow to update the firmware on the APM with a newer version, regarding the following:

Must everything be disconnected from the APM? I have read of usb port burning
What will happen with the current parameters and calibration of equipment with updating?
How can I backup the parameters and calibration to load on the new firmware?

Thanks

@Emarcus,
Unless your PC has robust USB ports or you are using a powered USB Hub, I would recommend detaching components from the APM to reduce the electrical load during programming.
Regards,
TCIII GM

And what happens to the calibration, setup and parameters?

@Emarcus,
After updating the APM firmware, hook all of the components back up and proceed to do the calibrations using the telemetry radio.
Regards,
TCIII AVD