Could I use saffron powder instead of saffron threads?

Yes, you can definitely use saffron powder, though I would use half the amount called for in the recipe (1/4 teaspoon instead of 1/2 teaspoon). I hope you enjoy it!

Absolutely. Follow the recipe and just measure out a 1/2 teaspoon of powder. Follow the directions in order to allow the powder to "bloom" to get their distinct flavor. Enjoy!