can this be applied over a brick wall outside? Also how many pieces in a box? Is it a lot of small pieces, or large pieces?

Brick is an excellent substrate for AirStone (inside or outside)...you should be able to adhere the AirStone directly to it as long as it’s in good condition and clean/free of dust. If the brick is painted, it's important that the paint is in good condition. If it's peeling, chipping, etc. you will need to prepare the surface as if you were going to apply a fresh coat of paint....scrape/sand it where necessary and then make sure the surface is totally clean before you begin. When you press the AirStone to the surface (with the adhesive on the back), rock it gently back and forth a bit, so that the adhesive compresses into all the little nooks and crannies! For an exterior project, be sure to use AirStone Exterior Adhesive. There are approximately 60 pieces of AirStone in a carton of "flats" (always amounting to 8 sq. ft.). They come in lengths of 4", 6", 8", 10", and 12" and are 2” or 4” high. Thanks!