Yes, "you" can be either singular or plural.
The conventional way to ask this question would be: "What are your names?" If you were asking only one person for his name you would day, "What is your name?"
(There is a small possible ambiguity if the person has more than one name. Like if someone was a criminal who regularly used fake names, the policeman might ask him, "Okay, so what are ALL your names?" Perhaps I should clarify that while people regularly have first, middle, and last names, we still refer to all of this as "your name". People say, "My name is Fred Smith", not "My names are Fred Smith.")
I'm not sure why you said "actual names" in your examples. The word "actual" would only be meaningful in the sentence if it is necessary to contrast with some non-actual name. I guess if you were asking a group of actors, you might want to make clear that you mean their real names and not the names of their characters in the show. Or if there was a possible ambiguity whether you meant their log-on id's to the computer system versus their real names. But normally, you just say "name".
As to your examples:
1.What are the actual names of yours?
Grammatically correct, I suppose, but awkward. A fluent speaker would be more likely to say, "What are your actual names?"
2.What are the actual names of you all?
Acceptable for casual speech, especially in the southern U.S., but would likely be questioned if used in formal writing.
3.What are the actual names of your?
No. "Your" is a possessive and does not fit here. It is an adjective with no noun to modify. You could say, "What are the actual names of your friends?", etc
4.What are the actual names of you people?
Fine for casual speech, but a little awkward. Probably would not be used in formal speech. Also, the phrase "you people" can be considered rude. It implies that they are members of a class that is different from yours and presumably inferior. I'd avoid this phrase except when you want to indicate anger or disdain. "You people get out of here!" Or, "I'm tired of putting up with you people."
5.What are the actual names of all of you?
That's perfectly good and grammatical. It's more long-winded than necessary, which may or may not be a bad thing.
The sentence
Will this action happened in the future?
contains a grammatic error: Will is a modal verb, and may only be followed by a verb in the infinitive: will + happen not will *happened.
Hence, the proper form is
Will this action happen in the future?
Regarding your mention of the use of this construction in orders and requests: it depends on which words you use, and on the situation.
Will somebody/you/anybody open the window?
is likely to be a request or order, while
Will this strong wind open the window?
is clearly neither a request nor order, unless Strong Wind is the name of a person.
Will summer follow the spring?
is unlikely to be a request, whereas
Will you follow this red car?
is pretty likely to be one, especially if said to a taxi driver by a passenger.
Best Answer
The most authentic-sounding is the second.
Option 1 is not valid. You are meeting (I imagine) in the room, and not "at" (i.e. outside it).
Option 3 is valid but likely overly formal.
Option 4 is not grammatical. "Where" and "in" do not play nicely together. When combined like this, they become "in which". So, you could potentially say (though I maintain it's formal/archaic): "Where/Which is the room in which we are meeting?".