1. What is the Interop Library
(As a reminder, my original question was whether I needed to copy over MYVFP.DLL or Interop.MYVFP.DLL whicj Dot Net Generated.
I meant to say the .NET Generated Interope Assembly

2. Do I need to register MYVFP.dll, Interop.MyVfp.dll or both
On the machine you'r deploying to you'll have to register. The only reason you don't have to register in the development machine is because when you build your VFP App as a DLL the compilation automatically registers it for you

3. What is VFPD11 file ?
It's VFP DLL not D11

However, if you just register you VFP DLL on the target machine and create an install project in VS.NET everthing should work.