If they must live long time in the void of space, they must be able to hybernate and have some kind of symbiosis with photosynthetic organisms
It is safe to decide that a space dwelling humanoid should have no lungs and breathing system. They would be useless, plus would expose to the vacuum a lot of mucose and thin bllod vessels.
Heat should not be a problem, as long as they don't touch anything: vacuum is a great insulator, they could have problems in dissipating heat.
The true problem is how to keep the metabolism working (because they can't have access to air) and how to eat.
About metabolism, these humans would be closed loops that need only light to live: their skin should be partially transparent and there should be some photosynthetics bacteria living under their skin. These bacteria recover CO2 and waste from the blood of the man and thank to light can generate nutrients and Oxygen that are released in the blood stream. Since this photosynthesis would probably generate a small amount of nutrients for a hot-blooded creature, they should pass the grater part of their time in hybernation, in order to save energies.
Obviously, they would have no escretory system, since they can't afford to lose any not replaceable resource (aka atoms heavier tha Helium).
Unluckily, if they have to grow, there is no way to find suitable nutrients in the space: probably they would be a kind of predator of other space-dwelling species, or would work for planet dwelling humans in order to receive suitable food.