There are no neighbors. The Air bnb she showed up at was A) accidentally double booked, and B) in a "neighborhood" that consisted only of decrepit buildings with the nice bnb sticking out like a sore thumb (and there is a plot reason for this later on). She also has a job interview tomorrow in the city but a medical convention is happening so she can't get a hotel hence why she agrees to stay the night with the guy. As for "mindlessly" going down the stairs, again, I won't say why as this is getting into heavier spoilers, but there's a legit psychological reason she does so. The three leads in the film have their characterization very well established so most of their decisions, even ones that from an outsider's view may not seem wise, make sense for each character to make.
And the antagonist in the film is more fucked up than anything in RE7. Maybe not as fucked up as that one thing in RE8 though…
And that tape is handled absolutely nothing like the tapes in RE7