"Is he laughing?"
Unfortunately yes. I guess grammatically correct way with this verb and this construction would be to say "Onko hän nauramassa?" but that is clumsy and wouldn't really mean the same thing as it would sort of imply a continuous action. With this structure you could however ask questions like "Onko hän kotona?" (Is he/she at home?") or "Onko hän poissa? (Is he/she gone?)
Is there an article someplace which explains when the pronoun is optional and when it is required? I am very frustrated over trying to learn the inconsistencies just by example (I know that it is not just Finnish that is like this, English also has inconsistencies which I just know due to it being my native tongue)