Short answers, pulled from the story.
The E-11 blaster rifle was constructed from a Sterling submachine gun originally used by the armed forces of the United Kingdom during the second half of the 20th century. Filmmakers modified the magazine and other components to fit the galaxy far away aesthetic.
Ben Burtt created the iconic sound of blaster fire during a family backpacking trip in the Pocono Mountains in 1976. He struck the guy-wire of an AM radio transmitter tower with a hammer while recording the impact close up to produce the signature crack heard across the galaxy.
Color coding helped depict opposing forces clearly to the audience throughout the franchise. Rebels employed red blaster fire and often attacked from the left side of the frame, while the Empire used green blaster fire only when TIE fighters were involved attacking from the right.
When a trigger is pulled, high-energy gas becomes excited by a power cell and converts into plasma that travels through collimating components like galven circuitry and focusing lenses within the barrel. Magnetic bottle effects hold the energy bolt together as it emerges from the weapon before dissipating due to inherent instability.
Adam Savage and Jamie Hyneman tested dodging blaster bolts in episode 236 of MythBusters and found average bolt speeds around 40 feet per second. Examination of film footage revealed neither participant could dodge the shots due to human reaction constraints so the myth was declared busted when both failed to avoid incoming fire.