Ok so I'm going to be converting some Dwarf characters for a friend of mine in exchange for some painting from him (I suck at painting and he sucks at conversions

). I'm going to be making a King, Thane
BSB, Master Engineer, Dragon Slayer and a model that could be either a Runesmith or Runelord. I'm making the models entirely out of only
GW plastics. So after talking about ideas for each of the characters, looking at some concept art from
WAR and searching through various Bits sites I have it pretty well planned out how I'll do each character but I do have some questions.
1. How do Dwarf arms compare to arms of humans? For instance could I swap out a normal Dwarfs arms with arms from the
IG or Empire range and still have it be right as far as scale goes? Or could I put Dwarf arms on a human and have them look normal? In short are the arms of Dwarf and Human models enterchangable?
2. Does anyone know any good tutorials on sculpting
GS beards? I'm going to be using seperate heads from the Dwarf range mostly from the Space Wolves and I'm going to be sculpting some
GS beards and braids onto the models.
3. Does anyone have any ideas on what I could convert to be suitable legs for a Slayer? I don't want to use any of the normal Dwarf legs and like I've said I want to stay with plastics from
GW, I just found a conversion someone did for Squats using Cadian legs that I might try but I'm still open to more suggestions.
4. Can anyone tell me what the Dwarfs are like from the Cannon/Organ Gun sprue? Are they assembled the same was as other Dwarfs in that their heads are attached to the front of the torso? More specifically I'm wanting to know how the engineer is with the apron is assembled.
Thanks ahead for any help