Did you specify a design? If a quilter says I'll do random stars ( or whatever) ask to take look at samples. If there are no samples available, then at least ask for a sketch. If they cannot provide a sample or sketch, look for another long arm quilter.
yes, you can take the quilting out. Remove the binding. You can either carefully clip the stitches on the back every so often, then pull the top thread off. If you work from the back and slip, it's easier to fix the backing than your beautiful top. You can also use the 'skinning' technique where you lift the backing a bit and cut the thread between the batting and backing. Just work slowly and put on your favorite movie.
If you used 100% cotton the holes left from the stitches will close if you steam them or when the quilt is laundered after it's been re-quilted.