Well there is still the chance that that alien on the Kelvin bridge was a member of Arex's race.
Nope. Alnschloss K'Bentayr
was a Monchezkean, according to behind-the-scenes material. And I see little resemblance to Edoans/Edosians.
Is Stephen Kandel still alive? It would be interesting to get his feedback.
As far as Memory Alpha and IMDb are aware, yes.