Thanks for the reply.
Yes, there are many similar units, I too recognise it as a problem. But i decided not to sweat too much about it, as, for example, having
10 unique units and
15 units, of which 10 would be unique and 5 would overlap, is pretty much equivalent; so why not.
Nurgle dudes evade because that's what they do in Warhammer (-1 to hit). Although from the point of view of common sense damage block does seem more appealing, I agree with you here. Maybe I'll remake it one day.
About 8 mb, the thing is, even if I ration it now down to, say, 5 mb, what will I do in the future, when I make additional 3-5 races? I thought that there's no chance I'll fit in in the end, so why not not-fit in it now

But! I do recognise that people might be reluctant to mess with the tool, so I have plans to upload a limited-version of one of my maps which would have less custom models and would weigh ~7 mb.
Empire actually doesn't use a Priest model, I just screwed up when printscreening them. The White Mage ingame looks like dismounted Archmage, but well noticed. Thanks for the Rat Ogre, but I actually came across that model and thought that it didn't look menacing enough for me, so I decided to stay with gnoll.
I put a lot of hope in a big campaign I'm making, but the progress is slow and I plan to make 30+ missions for it (will split into 3 acts). If it one day sees light (no sooner than in ~4 years I guess), mark my words, it will be epic

I hope to finish Act I somewhat soonish (<2 years). As of yet, I have 4 missions. Will post the link for them once I upload them here on Hive.