> Which was the first dinosaur to be called a ...raptor and why?
The first I know of is Oviraptor, which means "egg thief". The reason is
that one was found on a nest full of eggs, and it was assumed that the
eggs were Protoceratops eggs, and that the Oviraptor was stealing them.
It turns out, however, that they were Oviraptor eggs. So it probably
should have been called Ovimama, or something like that.
> Is there a connection between the oviraptor and the velociraptor when
> the first was stealing eggs while the other was killing with its claws
> and why are they both raptors?
Oviraptor wasn't stealing eggs. The same word is used with two
different, though similar meanings.
> Is it more common for other "raptor"
> species to eat eggs or to kill other dinosaurs?
"Raptor" is just a word. It can mean "thief" or "catcher" or "hunter".
Praying mantises have "raptorial forelegs" and hawks and owls are called
"raptors" too. This all comes from the Latin verb rapto meaning "to
seize and carry off, to hurry away, to rob or plunder". We get "rape"
from the same root, and the original meaning of that word was to seize
by force.