Liquitex Basics acrylic paint is cheap, and works really well on canvas. As a tip, use painters tape to hold the stencil in place, and put a book under the canvas to make sure the stencil does not move.
Sure! However, the Chinese gong was made to make sounds, not to be decorative. If it doesn't make sound, then it's not a traditional Chinese gong. However, it would be...
It may just make your angel unique. You could add touches of it throughout the whole costume, if you like. You could also add glitter to make it less spooky.
You should use heavy needles, such as those needed for the leather skin. Thanks to its ball point, this kind of needle penetrates thick fabrics with ease.