Of that you cannot be 100% certain for the reasons I have already stated.
Dinosaurs as they existed at that time do not exist today.
Birds are different, just as we are not reptiles.
Birds ARE dinosaurs...you don't seem to appreciate that there is no real distinction...biologically speaking.
Not really, just as we aren't reptiles, even though we share the same common ancestor.
Today, we have a several types of complex life: birds, insects, mammals, fish, reptiles, etc. Dinosaurs are among this classification; there is no evidence that any creature that fit that classification has survived to this day.