Maro brows (麻呂眉) is basically the short, thick eyebrows you might have seen before on characters that are more on the traditional Japanese side. An example close to home would be Zounose's Suwako.

Tasuki (たすき) is the strap you might have seen some characters use to tuck up their kimono sleeves when working.

And when people in Touhou say "vengeful spirits", the specific term they're using is Onryō (怨霊).