All DLCs (of SCS) are compatible with the Multiplayer apart from some parts of the Raven DLC which will be supported very soon.
Remember, when there is a new DLC, just wait for it to get supported
For the last part of your problem, it is a common bug. You just need to wait for your game to catch up with the MP time or you can try to fire all of your drivers which can help your game to speed up.
We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.