Regarding DLLs: Ch40zzC0d3r already said it but what works fine for me (for 3 custom DLLs) is to use special acknex plug-ins/ DLLs.

Don't know about the launcher stuff but I think the Steamworks Dev Forums (should) have some threads from people with similar problems. I don't know your game/ product but personally I hate launchers, they are so 1996. I don't think anything justifies having those instead of adding the config stuff to the game itself.