@sEventoRii, if you are studying English, the way that the teacher is presenting these forms to you is part of a larger scheme or plan. You are not getting them in isolation (that is, separate and unrelated to anything else).
If you do not understand them the way they are coming to you in your lesson, you will have to go back to the teacher for your answers. We don’t know how they’re being taught to you. They sound unnatural to us all by themselves, even though some of us do clearly understand them as grammatical constructions. I’m afraid that we will just confuse you by taking wild guesses at what this lesson is supposed to be about.
@FutureMemory, yes, I think you have: “I’m about to lose my temper. You’re to (you are to) go to your room at once. If I were to do what I please right now, I’d smack your bottom.” Those are forms of the verb “to be”—to be about to, to be to, and were to. We just never use them with the infinitive; we conjugate them.