Other than the thimble, everything else for her should be normal size and all the things that you consider important to have when you are sewing. I was sewing by the time I was 8, because I just loved it. I was lucky that my Mom & Grandmother went ahead and taught me.
On the other hand, I wouldn't give her a rotary cutter until she is a bit older. They are just too dangerous. Perhaps you will be the kit maker, doing most of the cutting, so she can just sew. That will give her so much useful experience.
I have a GD that is 10 and ready to sew, but we aren't together enough. I plan to change that in the summer of 2015.