#1--the newly created design gets lost
#2--acceptable. What does a creamy color similar to the background of the fabric look like?
#3--maybe a bit dark but a nice blender and works. Like the others who have suggested, a sage green or one more like what is in the piece would be worth auditioning. I'm not a great fan of that much black. Black tends to fade and become brown. I like the idea of using setting triangles and then sashing to set each design to itself. Beautiful quilt coming around!