As for a project involving both Slof and Rebel, that would be news for me. I tried searching for what you were describing and didn't come up with anything. If you find something more definite about that, BFG, be sure to let me know.
Most of my information comes from private messages with Slof that started with a request for essentially this same thing on the TESNexus forums. I know that the Hellhound mod she put up not too long ago was based on some of the work they've done, but I've heard nothing more about the project since. I'll keep you posted if I do hear anything, but I wouldn't expect much anytime soon.
Using already available resources, I'm thinking I could definitely at least add minotaurs, liches, zombies, spriggans, spider daedra, and goblins (assuming the models I'm looking at accurately cover the necessary parts). Xivilai and Dremora have races made for them that could be used to fashion female versions, though I'm not sure how they should be clothed. That leaves imps, ghosts, wraiths, and flame atronachs that I'm clueless about. I was thinking the feminine equivalent of an imp might be made from a sprite or fairy, but so far I haven't found a mod for that. I'm sure I saw one in the past, though. Any suggestions?
For what it's worth, a female Lich has already been created and posted on TESNexus (link removed - I didn't realize it was advlt content!). A female Dremora actually already exists in-game though not many know about it--one of the Dremora Markynaz archers, ID 146C5. Female goblins also already exist. Regarding the rest, I definitely think the game could use female models for imps, minotaurs, ogres, zombies, and the various animals (except gendered horses and deer, which already exist in game or have already been modded); I'm not sure if spriggans, trolls, spider daedra, or especially atronachs need genders though, for reasons I can get into if anyone cares.
As a realism buff, I'd strongly prefer any such work not be extreme like it is in "sixualized Monsters". For example, the female Xivilai and ogres should at least wear a loincloth like the males do in Vanilla; and strategic fur placement on the female minotaur model could be used as it is on the male. Such censoring, if in keeping with the vanilla game models or if realistic, I think is fine. But I dislike censoring if it's obviously being done to the detriment of realism. The fact that (except for the horses) Oblivion uses "Disneyfied" animal models has always mildly irritated me, even though I understand why they did so, and I am probably in the minority on this topic.