For http://elsweyr.project-tamriel.com/, I would like to use Cait Sith's cats and kitten models. Do I need permission to modify them (not just the texture) and who should I contact?

I think Cait stopped modding Morrowind years ago; Kagz may still be in touch with her - he used many of her models in his mods. You can find his page on Wolflore if you type 'Kagz mods' in Google.

What does the Read Me say? There are 3 mods on the Nexus using her models, and I know of other's. I vaguely remember that she would allow use for other's to use the mod if credit was given. Now, this was years ago, so my memory is fuzzy on this.Do attempt to get in contact through Kagz as her website and domain seem to be abandoned at the moment.

It says you can modify the textures, but there's nothing about the models:

I think as long as you give credit and change texture/mesh names/folder to avoid conflict with other mods using the originals, there should be absolutely no problem

Thank you!