Is dinosaur a reptile

Answer 1

This is information gleaned from the website below

A reptile that lived between 220 million years ago and 65 million years ago, walked with its feet below it's hips, was maybe warm-blooded, had neither flippers or wings, and is closely related to modern birds. They just aren't oversized lizards.
Yes, because they are members of the phylogenetic clade Sauropsida ("lizard faces"). Note however that the term "reptile" is a paraphyletic (unnatural) assemblage of animals because it excludes the birds, which are also dinosaurs (since they descended from dinosaurs) and therefore reptiles.

Answer 2

No, dinosaurs are more related to birds and crocodilians.

Answer 3

Yes