I can make myself a light table if I need to, my sewing desk is glass and I've clipped a spotlight underneath it for this purpose before. But with fabric this light, I really don't think I'll need to. I'll be tracing over black lines on white paper, after all. My dining table is already pretty light, being birch, but I may try your tricky with the white sheet to see if that helps at all.
I've ordered two 10g balls of thread, along with a variety of colours to increase my thread stash. I went with DMC in the end, they're cheaper and I already have a shade card for them. Although it's still incredibly hard to tell, and for some reason they have a prejudice against turquoise. I picked a shade of orange which looked like it should work well. I think DMC are reliable enough that if I run out, I'll be OK getting thread from another batch. It's not as if it's going to be a solid area of thread, such as you'd get with crochet or embroidery.
The design is adapted from one I found on a Welsh quilting blog. I've spent a while reading books on Welsh quilting and saving images from online sources, so I'm fairly good at this sort of designing by now. I did Welsh quilting on a log cabin quilt last year, it turned out a treat. I've tried out drawing a quarter of the design full-size already, and the spacing works out better than it looks in this sketch.