Those are awesome! I need to learn how to use greenstuff and have a go at something like this. You have a talent for seeing different uses for kits -- I would never have thought to use Norman Knights as a basis for Pancerni! 
I'm not even particularly good at it. I try to limit my sculpting needs to fur and chainmail, which is why I get so clever with the kitbashing. Basically, I just decide what unit I want to have, then I browse the internet for what plastic kits might come closest. If it looks like my limited GS skills can bridge the gap, I go for it. Anyway, for greenstuffing, practice makes perfect (or at least practice makes adequate). I'd say, consider investing in some greenstuff and
some of these cheap plastics and just start messing around. The miniatures are supposed to be Persian infantry, but with a bit of creativity and some spare bits, they can be lots of things. Also, it's my understanding that there are good greenstuff tutorials around the internet.
I like them too. Hmm, I wonder what historical miniatures I can convert the Moria goblins to...
Oof, ya got me. Too armored for pygmies, too short for anything else. Maybe a better-equipped, alternate history Children's Crusade?