These are great questions, Martin. Using questions that begin with "what" and "how" usually provide more information than a simple yes or no response. The "why" question can be a bit tricky in my experience. Sometimes (depending on your level of rapport with someone), it can be taken as being judgmental or accusatory. For example, "Why did you decide to go to school now" can make someone defensive. The usual response to a "why" question begins with "because..." - or a need to prove something. This can break rapport so I typically suggest using a "why" question only with a softner such as, "I'm curious....why..." or "Perhaps you can tell me why....". Does that make sense, Martin?