We have a .NET app that consumes COM-objects in different DLLs, also used in the VB6 part of our app. When referencing a COM library, Visual Studio 2012 creates an Interop.x.DLL and references that instead. Should I be distributing Interop.x.DLL from the build machine or regenerating it using some .NET command-line tool? What tool? What is the best practice for deploying a .NET app that references COM?
No, that is not necessary anymore since VS2010 and .NET 4.0. You simply set the Embed Interop Types property of the interop assembly reference to True. The default setting.
With this option in effect, the interop types get copied into your own assembly, as though you had written the [ComImport] declarations yourself by hand. And only the ones you actually use in your code. The feature pays off most for large ones, the Microsoft.Office.Interop assemblies in particular are very large. But of course always handy as well for small components since you don't have to deploy the interop assembly anymore.