We do not support installing the AstroBox software on an existing Raspbian. There are too many dependencies and it would be too much support work for us.
Your bonus Question:
AstroBox is software (and even a complete product) that acts as a 3D Printer Controller to connect the printer to the AstroPrint Cloud. Here’s more information: https://www.astroprint.com/products/p/astrobox
AstroPrint is a) the name of our company and b) our complete software platform which includes, the AstroBox, mobile and desktop apps and a cloud service. This image describes it well: