we cant know, of course. but i think your mistake is assuming heaven is something physical, therefore can be compared with physicallity we know in out own mundane thinking. people often do that with Gd as well. but all thats stuff is spiritual, untangible, on a totally different level. we cant begin to understand it because its nothing like what we know.
No one can say for sure. If you mean night as a passage of time then I don't think so. But if you mean as in the setting of night time maybe. Some think everyone will have there own heaven. So if you want night then why not.
Id say most could connect this with there faith.... To believe in God It would mean that your God is perfect in every way with out flaw and with that comes pure light so bright that it can not be described so with that Id say there is not a night sky but then again if god wanted there to be a night there would be! Awesome Question
( 13 ) [They will be] reclining therein on adorned couches. They will not see therein any [burning] sun or [freezing] cold. Quran(76:13) ------- "The scholars said there is no night and day in Paradise rather they will be in eternal everlasting light. They will know when night comes because curtains or screens will be put up and doors will be closed, and they will know when day comes because the curtains or screens will be taken down and the doors will be opened. This was mentioned by Abdul-Faraj ibn AL-Jawz?" [AL-Qurtub?, at-Tadhkirah, p. 504] ]