i think that a site dedicated to the tamazight language (and berber languages in general) will be helpful as this branch of the afro-asiatic languages is a very important missed link that can even help understanding other languages such as spanish or chadian...
There doesn't seem to be one. Stack Exchange sites are created from proposals on Area 51, and proposals on Area 51 are created by users — i.e. by you. So go ahead and propose a site!
I see that you've already done it.
The next step is to promote the site. To start with, you need to find experts — at a minimum, you'll need to find