I use FSX. As I understand it "add on mgr" isn't used anymore
Nowhere we ever said the Addon Manager is not used anymore. It obviously is, and it comes with every product. What is not needed, is a SEPARATE installer for the Addon Manager, which USED to be required to update the Addon Manager itself without having to download a whole product installer. THIS is not required anymore, since the Live Update can update all products in one go.
I have searched for anything using the "Y" key other than "slew", but have not found a thing
Please clarify your problem. I'm not sure you understood what the Y key stands for.
Yes, it IS the standard Slew key but, since GSX places the airplane in Slew when editing the airplane config, the location of the vehicles and the pushback route, if you need to Exit from these modes ( which means exiting from Slew mode ) you press the key to exit from Slew mode which, of course, it's still Y.