Wish I had seen this earlier..... I have spent a lot of time looking at YouTube at many different things. Superior Thread has a series of videos discussing thread and needles. I spent a lot of time looking at those trying to understand (what the vast majority of you already know!!) I even sent them an email asking their advice (So Fine 50 and top stitch needles, and I get the titanium coated needles). They will respond to you!!! Now I have seen a lot of different things about thread, and I will not go into much detail (I have already given you all I know!!) But I strongly recommend you go to you tube and check out the Superior Thread videos by Dr. Bob. I'm still learning, and currently have Superior, Gutterman, and Coats & Clark. I cannot tell you if one is better than the other...again many of you can. But I have found it interesting to search and learn.
And I wish I had gotten back here sooner!!! Hope this helps.... just remember this info is from an old motorcycle bum who is learning how to sew!!!