For me, the most disturbing aspect of your encounter (again, thank you so much for reporting!) is his questions. Like you said, they make no sense.
It's almost as though he was looking for or "targeting" (and I don't even know if that's what this man was doing, but his behavior certainly sounds suspicious) someone who lives at the complex, he thought you were that person, for one reason or another (e.g., you drive a similar vehicle), but then once he got out of his car, got a closer look and started to doubt your identity or realized you weren't the person he was looking for, he knew he couldn't just get back into his car and drive away without saying something, so he came up with these nonsensical questions.
I really am not sure if this is relevant to Danielle's disappearance, but given that it happened within an hour or so of Danielle leaving work, I think it is entirely possible that it is. But the fact that LE hasn't asked you to help them with a composite sketch or reached out to you in almost two weeks (IIRC) leads me to believe they have a different POI (or maybe more than one of them) in mind. I mean they could have at least released a sketch and said, "We just want to speak to this person. The person is not a suspect," etc.