meter measure
"Meter" is a Greek root. It comes from the Greek word "metron," which means measure.
Assuming you mean cred- as in incredible, credibility, etc., it comes from the Latin word credere (to believe).
uni (latin) mono (greek) both of them mean one
Yes. Equinomorph does mean horse-shaped in Greek and Latin.
Yes. Heptanocular mean seven eyes in Greek and Latin
Yes. Psychovore does mean mind-consumer in Greek and Latin.
Yes. Hematovore does mean blood-consumer in Greek and Latin.
Yes. tetranocular mean four eyes in Greek and Latin
No, it's from Greek meter "mother" and polis"city."
Demeter is not a Roman name, so has little meaning in Latin, it is Greek and the meaning is "Earth (De=Ge) Mother (Meter)".
It is correct to say biantibrachial mean two forearms in Greek and Latin.