Thanks!
That's a horn, but you could easily call it a standard if needed
It's been a while from when I painted these, so I'm not sure about the colors. All models were sprayed black.
The green is most likely Dark angels or some other dark green, and highlighted using Vile Green and Vile green + white for final highlights, if needed. I don't know if Vile Green is still in production... (It's an old "Bolter shell" bottle)
Beards are first coated using a mid brown, (but not bestial brown, most likely it's Snakebite Leather), then drybrushed (or overbrushed/highlighted) using a sand color, such as bubonic brown and final highlights using bleached bone. I think. At least that's what I'll try first when I start painting again

Sorry but I really cannot remember any better. I tried comparing the colors with paint pots, though, so it's my best guess.