I think most of the Romulan material is for higher ranking characters and perhaps just for Vice Admirals / Lt Generals. Don't know if that explains why you're not seeing them.
I've only done two missions myself, one was releasing captured Romulan ships and another was disrupting the Tholians from building a web around the Vault. I found my engineer to be best equiped for handling the Tholians.
I normally don't bother with pets, but I think the little pups are funny. I didn't know if they would expire if not grown to full size by the end of the Winter Wonderland.
I had one candy striped pup follow me around during the snowman attack. Funny as hell because I'm constantly moving during the fight.