We have a code generator that munges the schema of a given database to automate our inhouse n-tier architecture. The output is various C# partial classes, one per file. >
Take a look at Narrange.You'll probably need to automate these things as part of the build.
Not sure if it meets all your requirements though. To quote:
NArrange is a .NET code beautifier
that automatically organizes code
members and elements within .NET
classes.