Connection killed by firmware update and issues with RC-IN

I have an old quad frame that until today was running a 3yo version of Arducopter without any issues. I connected the Pixhawk in it to Mission Planner after responding positively to the invitation to update MP to the latest version (1.3.68). The FC connected OK to my Win7 64bit PC and allowed me to view the setup. For some reason I decided to update the copter firmware on the craft to the most recent version available. Mission Planner asked me to disconnect the board, press OK and then reconnect - which I did, but the firmware would not upload to the board. Eventually I discovered that the driver on the PC had been disabled (or at least wouldn’t work). I noted that the STM32 driver was missing from it’s usual place under Ports but had been replaced by something called FMUV2 under “other devices” in Device Manager - for which neither my PC nor Miicrosoft (apparently) has a driver. When I went to connect my Taranis X9D to the PC, the driver for that was gone as well - but I was able to restore that with Zadig. I have been unable to get my PC to use it’s USB driver for the Pixhawk and have had to use another PC to configure the FC. Is there any way to restore the damage that I seem to have done?

The second issue arose when I attempted to set Channel 6 to RTL and Channel 7 to Autotune, options that I have been using for years. The Wiki here says that I can use values 4 for RTL and 17 for AT and set them in the RC6 and RC7 parameters. However I don’t see any way to set anything in the RCx parameters other than ranges, reverse, etc. The options are not available in the SERVO functions either. Clearly I am misunderstanding something basic, could someone please advise how to insert the functions that I want to continue using? Thanks.

Uninstall the device drivers (try unistalling MP) and install them again. That will fix the missing board.
Take a look at the RCX_FUNCTION parameters.

I eventually discovered by searching the FPL that channel 6, by default, is used for TUNE and (seemingly) cannot be changed. The channels 7- 12 functions are not set by RCX_FUNCTION parameters (I wrote above that I could not find a way to do this) but instead by the CHX_OPT parameter.