Placement of characters in a simple question
Both你午饭要吃什么？and 午饭你要吃什么？are right

These two sentences all mean what do you want to eat

“你要去哪里吃午饭 ”is correct in grammer，but it means where do you want to have lunch，it does not means what do you want to eat

吃午饭，你要去哪里？Although we can understand what the sentence mean,we simply don't speak this way

你在哪个地方要吃午饭？should be: 你要在哪个地方吃午饭？