No it's definitely not plastic but particle board like you said. It must be some sort of vinyl covering on it to give it that texture. Should I even attempt to clean it or should I just use some adhesion promoter before paint?Sweet,good job.
So its plastic trim?
I've never seen that before.
As for painting it,take a look through here.
http://www.stangnet.com/mustang-for...dashboard-how-to-warning-tons-of-pics.746918/
No clear coat needed,though I would suggest an adhesion promoter before paint (though I didn't use any and my dash still looks great.)