Wow, this is very well done and is a fantastic resource for any new player. Thank you for making it!

As for the Battle Armor thing, I know that China eventually gets the option of buying Advanced Cloth (the purple clothes) in the Group Shop, which is good to know.

I unfortunately don't know about threads, but god*, they are expensive and are impossible to rank up. I'd advise you to go for magatamas, which give a concrete boost in strength, or refinement (getting all your characters to 3-4 refinement), which has a chance of failure, but a larger boost.

I'm sitting here at 45/50 with the battle armor and after like 2 weeks of defeating difficult, unable to level up my battle armor to rank 2. :