Goodness, this has me thinking again about building a separate studio on the property.
I like the idea of lots and lots of electrical outlets at about waist high. I don't think I'd like wires hanging from the ceiling although I know lots of people do like it. Lighting is super important If it was me, I would focus a lot on this. I'd paint the walls a light color and I'd have a hard floor. I like the suggestion to put furniture on lock-able wheels so you can rearrange things. After you get settled in to your space, you may change your mind about where you want things. I love having a design wall and plenty of shelving behind closed doors.
Won't this be exciting for you! Keep us updated.