the particle 'か’ is used on in formal speech with formal conjugations. To ask a question in informal speech you would simply raise your voice at the end of the question to make it sound like a question (if that makes sense). As for the the '5 W's', だれ 何 それ・これ・あれ（These are really the words for 'that' however depending on which one you use I'm pretty sure it is basically the same as 'which' どれ いつ Also its to remeber that there aren't just 5 like in english for exaple there are many forms of 'what' in Japanese that change based how you would use them. がんばて！