That's a cute dress and an adorably beautiful child. I sew clothing also and I have never worried about the weight or type of thread. I use whatever I have that matches my fabric. I also seldom use patterns--it just takes so much time to pin them on, then take the pins out. But, I should mention that I used to use patterns and learned how to do that first. The clothing that I make is usually simple stuff like jumpers, peasant skirts, peasant blouses, tshirts, shorts, pants, etc. I did, however, last year make my dd a sheepskin coat. I didn't have a paper pattern but rather cut up an old sheepskin coat that was too small and used that for the pattern. I recently made a housecoat for my sister. What I do is take something that fits and use that for a pattern just by laying it out on the fabric (it's all in the folding) and that way I don't have to pin. I love to make clothing and find it just as easy, if not easier, than quilting.