LMP

Hi, I plan to swap these two belt straps, and I am new to working with leather. I plan to use a saddle stitch. Can anyone recommend what thread would match the original in terms of weight, text, size, brand, etc.? Also, I may end up dying the brown strap black at some point in the future, so non-synthetic thread that will take dye would be great. Thanks.

I always hear that mixing Fibings and Angelus dyes has bad results. I am wondering what that result is? a color issues, bad chemical reaction, etc. Same for SUEDE dyes? I am wondering because I need to darken my only green suede dye (Angelus), and the Fiebings Suede Black just happens to lean green, and very similar to the hue I desire. It would be just perfect if I could add that instead of the Angelus Black which leans a totally different way. I tried a swatch and it seemed to work.. wondering if there really is a bad result, and is it something that would show up later?... like causing the dye to do weird things as it cures, etc... Thank you. I would love to hear from someone with first-hand experience. Thank you.