I LOVE the NS bits, we have them on several of our horses and they all go lovely in them.
With regards to the waterford - this is not a severe bit as long as you have nice hands, it's when people saw that it becomes harsh.
If you think she would like a lozenge mouthpiece why not try the NS...
Our sand school is very deep on one side and not very deep at all on the other, I think the base underneath the surface isn't overly level but im not 100% sure about that.
I was wondering would an arena leveller move more sand over to the other side where there isn't much or would I need to...