I have a very eager, extroverted and dominant student. This is great, but he has a bad habit of asking questions which are off topic and they often need an entire lesson to cover them properly. Is it acceptable for me to tell him that I will come back to him after class or promise to prepare a lesson on the subject he wants to discuss? I do always try to briefly attend to his questions, but that often leads to more questions and the next thing you know 45 minutes have passed. I find it quite disruptive and the other students lose focus. A couple of the other students have complained about him. I should probably have a private chat with him after class, but I don't want to say anything that will dampen his enthusiasm. If I don't deal with it now, though, I'll soon lose my temper because it's quite irritating. He also likes to argue and is always comparing American English to British English and often blurts out the difference in pronunciation. He also uses a lot of slang, which the other students don't always understand and it has to be explained. I speak Standard English with Received Pronunciation. He thinks my accent is strange and sometimes laughs at me. He's used to hearing American accents, I suppose.
He's on the right level, according to the results of his placement test.