I think these might be the answers to your questions.
Q. What kind of decal are you using? Inkjet printer decal or Laser printer decal?
A. Inkjet paper. This depends upon your printer.
Q. Where do you manage to buy these decals from?
A. He makes them himself, and buys the paper from www.beldecal.com.
Q. How do you print the decal?
A. You make the decal and then print onto that paper, like a regular.