It is literally impossible to be lost or unsure of what to do. Two consulate employees are in charge of instructing the interviewees from the gate to the official. It's important to be ready and have your documents in order. They are not requiring the 5x5cm pictures anymore - those are taken at CASV along with biometrics. Further proof of relationship was also not asked - although I recommend you still bring it. You never know! My interview was in english and I was asked questions about the relationship and the only thing I was asked that wasn't information we had already provided was aboout my proposal. After less than three minutes, the official said everything looked fine and my visa was approved.