Yes to both questions.
The name of the experience of being somewhere before is called
deja vue.
https://en.wikipedia.org/wiki/D%C3%A9j%C3%A0_vu
This article says it is common to about two-thirds of us.
About your first question - when I start thinking about how enormous the universe is and how insignificant people and their problems are in comparison to the size and the amount of time it has existed sometimes I get a sense of unreality.
But really I think it may be a more clear picture of reality. It reminds me, comfortingly sometimes, of how narrow my vision can be.