Launching Applications using a Button
How can I set what application is launched when a key is mapped to Application1 or Application2?
You can set Application1 / Application2 in Side Key Settings ([Start]->[Settings]->[Buttons]-> Side Key settings)
If you want to launch IE with Application1, you can set the value as shown below in registry.
[HKEY_LOCAL_MACHINE\ControlPanel\Keypad\SideKey]
P1Path = /Windows/iexplore.exe
P2Path = Application 2