I can identify a few of those things, if anyone is interested.
"Concept Art 22" depicts an Izlom, which is reintroduced in a few mods. I can't forget this one because it's the only thing that actually scares the hell out of me in-game. Oh, gods, the way it gallops at you...
"Cut Material 03 (Rendered)" is a Dwarf, aka "Burer", which are also reintroduced through mods. Personally, I think they're more annoying than frightening.
"Cut Material 05 (Rendered)" is a Poltergeist, the invisible buggers that throw crates and fireballs at you in Lab... X-16? I forget.
"Cut Material 02 (Rendered)" I'm pretty sure is an early version of the Controller mutant. Or, just a young one, when it still had hair and was free-spirited enough to gallivant about sans-jeans.
Great finds, btw. I love this stuff.
EDIT: Also, the two-headed thing in "Cut Material 01 (Rendered)" and "Concept Art 21" is a Chimera. I
think the midget things in "Concept Art 23" and "Cut Material 06 (Rendered)" are Gnomes.
And this is the Tark: