Do "You know..." Questions need question marks

I'm not quite sure if the type of questions I'm asking about count as indirect questions, so I apologize if that's what I should have put in the title. Do you need a question mark when you're phrasing something as a question, but it isn't a question? Particularly, questions when, if spoken, would have no upward inflection in your voice at the end. They can either be "you know... right?" or "you do know...?" or even have both. There are three particular types I can think of, so I'll give examples with the three forms of asking I just mentioned. Sorry if this whole jumble of text makes no sense. Anyway, here are the examples.

1. A question that's really an opinion: Someone says something stupid, so you say, "You know you sound like an idiot, right?"
2. A question that's stating the obvious: Someone wants to leave, so you say, "You do know there's a door right there?"
3. A question you know the answer to: Someone is sitting in your chair, and they know it's your chair. They can clearly see there's another chair right next to yours, so you say, "You do know there's another chair right here, right?"

In all of these cases, I either expect no answer, and/or I know the answer. In any (or all) of these situations, should the sentences not end with question marks? Like I said, if you spoke them aloud, you wouldn't have any upward inflection in your voice at the end.

Thanks, and I'm sorry if the format of this post is weird. It's my first time using this website.

EDIT: Ooh, sorry. Just remembered another; I knew I was forgetting something. It's when you know they don't know, basically; you're informing them of something. "You know, that's the fifth time that's happened today?" You're not really asking them if they knew. You're telling them.

Solution 1:

The answer is very simple. All the questions you cite are rhetorical questions. Rhetorical questions are used for effect. The whole point is that no reasonable answer is sought because no reasonable answer is possible.

How many times must we listen to their promises of universal prosperity only to be betrayed once the election is over?

The rhetorical question is called a question because it is cast in the interrogative form.

The examples you give illustrate the use of this device for the purpose of sarcasm.

They are called ‘rhetorical’ because in ancient times orators (‘rhetors’ - in Greek ρήτορες) used them.