I do know that on my Brother, your presser foot has to be UP for the tension to thread correctly.
Don't know about the thread breaking. It could be there is dust in the bobbin area, perhaps thread is stuck in the threading area, tension too tight, needle not large enough for the thread. I just try a gazzillion different things and sometimes it works and sometimes it doesn't. Frustrating, I know. You should have seen me yesterday! Once I threatened to get out another machine and it started to play nicely - for a time, anyways.

Hugs,