An ActiveX installation on PC can be verified by finding its ProgID from OleClass property in the registry.

A version of VFP OLE DB provider installed on computer can be retrieved from provider itself or from its DLL through the registry.

The files associated with VFP are opened in a new instance of VFP when double-clicked or 'Open' verb is executed on them. It's configured in Windows not in VFP.

MSDN:

• Environment Variables
• SendMessageTimeout Function
• WM_SETTINGCHANGE
• WSH RegWrite method