If you are going to send this out to a long armer, you should not quilt anything on it. Don't put the layers together either! If you quilt on it now, she may not accept it. And before you leave a top with her/him, you need to sit down and talk about what you want on this quilt. Any special things you want , sketch them out. Each long armer has their own comfort level. Some only do pantographs, some only do custom (what you are thinking of is custom). Get an estimate. (don't forget to breathe! Custom can be pricey!
If you are going to quilt it, yes, by all means draw it out. If you cannot draw it freehand, you probably won't be able to quilt it freehand either. I would suggest Golden Threads paper. You can draw it on some thing else, to get it just the way you want it, then trace it on the Golden Threads. You pin that on to your quilt and stitch right on the lines, picking the paper off after quilting. This is all done on a competed top, not just on the medallion. pounce works on dark fabric, but you would have to do that just prior to quilting. I have not had luck with it staying on very long (just my opinion). If you have not free motion quilted before, by all means, get a practice piece and work on that first. Its not as easy as it looks. You will be upset if you do all this work on the top and then have trouble with the quilting! (ask me how I know!)
I hope this has not been too much information and has helped at least a little!