It's definitely a beautiful dress. In my opinion, the design seen on the front (starting from the waist and going down) should be continued to the back of the dress. Since the dress and dupatta have so much kaam on them, I think it would look better if the churidar was plain. I mean you would also accessorize with jewelry, so u don't want to go overboard. The churidar would look best in blue.
If you're planing to sew/design an outfit similar to this one, then you can ask the tailor for their suggestion about what design should be on the back of the dress and for churidaar. A professional would be able to give some nice suggestions. Print out the picture of the dress and take it with you so the tailor can get an idea. The reason I'm saying this is because my mom, sister, and I print pictures of outfits from the Internet and after writing down our measurements on them, we give the pictures to a professional tailor to sew the outfits. It works out quite nicely! Best wishes:)