Just solved my problems, made a more clean install, after uninstallation I removed rocksmith registry files. Installed rocksmith once more and added the .dll file. Rags, answer to your questions. 1. File needed to be able to play custom dlc. 2. The song you have to buy to enable custom dlc. 3. The previous site where you could find custom dlc. 4. Program that you do not have to use, unless you want to create new songs. 5. AppID is a unique ID for each of the songs you buy from the rocksmith store. The d3d9x_42.dll is a tweak that changes the games requirement for unique appID for each dlc song. Most cdlc songs you download has cherub rock as appID and therefore it's required to play cdlc.