This is jaw droppingly amazing! First, welcome to the board, second you are absolutely amazing to have figured out how to do this with your computer then to have the tenacity to see it through.
Do you want this to be a quilt in the traditional sense, ie 3 layers sandwiched and then held together by stitches? It would definitely stabalize this work of art and also make it functional that you could incorporate a sleeve and hang it or actually cuddle up with Mr. Hiddleston.
I would definitley consider a longarmer but one who is very good and be prepared to pay the price. But a good longarmer to do this quilt justice will not come cheaply and someone who will do it cheaply is likely not good. You don't state your location but there are LAers capable of doing this wonderful work of art justice all over. I would highly recommend they do the quilting in either silk or invisfil. Both are very fine threads that will sink into the fabric and enhance your work not overtake it. If you google images of portrait quilting you will get some hits of the kind of work I am recommending. Here are a couple links to illustrate what I am talking about. Hopefully they work.
http://stitchesoftime.files.wordpres...ks-quilt-2.jpg
http://www.quiltingdaily.com/cfs-fil...f-portrait.jpg