The first color thread I would try would be a tan/taupe variegated thread...I would pull off a bunch on the burgundy pink area to see how it looks there. You can tell how the color will look by doing that.
As for the quilting, I am always at a loss on 'how' to quilt something. I have a baby quilt that has been pin basted and waiting for 10 days and thinking I am going to end up just meandering simply because I cannot make up my mind what to do and it needs to be done by the end of April.
as to HOW to quilt it,