Deployment of Interop dll

I have a C# utility which talks to MicroStation using the COM Interop layer. It has a reference to the primary interop assembly (bentley.interop.microstationdgn.dll) which resides in MicrosStation installation directory.

Now I wonder what should I do when I want to send it ver my users, which have different versions of MicroStation or PowerDraft?

Should I include my copy of the interop dll in the distribution, or it must use the version that is installed on the target computer?

Can I hope a program compiled with the dll from V8 XM would also work with V8i?

And finally does anyone know what if it legal to redistribute the interop dll? Microsoft's PIA packs have a special license attached, but I could not find anything similar for Bentley's ones.

Have I missed something?

/Elias