Skyrim model/skeleton creation

[dardar]

How easy is it to do either of the following:

1. Create a new creature model that can be assigned to an original creature skeleton?
2. Create a new creature skeleton and model?

I ask because after looking at a mod that adds the Tsaesci Race into skyrim, i noticed that included within the mod was a summonable "snake" which uses the skeleton of an ice wraith but a custom snake model. Unfortunatly, this made the snake bounce around similar to how a wraith would do. My original thought was whether it was possible to make a new skeleton for a snake, then whether it was even possible to add new skeletons at all.

Sorry if some of the answers to this are obvious, i honestly don't know the first thing about creating mods of any kind or even what software is used, though if i could find this out i would love to attempt making my own creatures.

 

Any info is greatly appreciated.