What kind of heat gun do I use?

An iron might leave behind stains if the paper is light colored; try a hairdryer instead.

Inkjet is ideal as the ink easily transfers, but laser jet works, too. It will take a little longer, but there's not a big difference in quality.

Paralysis, and prolonged exposure (especially to the neck or heart) can kill. You could incapacitate someone, but if not careful, could outright kill or permanently paralyze.

Matte spray paint. I recommend Krylon Fusion. Also, you might want to use a clear coat to protect the paint from chipping.