They lived over a vast range of time. During most of that time it is believed that it was much warmer than today. Some dinosaurs lived in the Arctic and had very large eyes and optic lobes so it is likely that some of them could see in the dark. Anything that a bird might do you should expect of dinosaurs. It is very likely that some of them hunted at night in my opinion. It is a popular notion that mammals came out at night to avoid dinosaurs but that is probably just some unfounded bias from the days when they were considered just reptiles. I don't think it would take long to see one in most places. It depends though. Some lived in deserts and in places like that they might be spread out pretty thin unless you are by a water hole or something like that. Many of the places would have been crowded with them assuming that there was enough rain to provide lots of food.

Dinosaurs lasted for 135 million years. To adswer your question one would need to know where on earth the time traveler and when he was.

This is so sifi question.

if a human time traveler went back in time to the age of dinosaurs and pitched camp, would he be mostly unharrassed untill the morning? How long before one would make a first sighting of a dinosaur? What would the landscape appear as? Air, heat, humidity?