Unknown; probably in two-digit megajoules at best. See blaster firepower for details.
Longer than that of blasters.
Blaster rifles seem to have semi-auto and burst-fire mode, as seen in RotS. However, during Original Trilogy, only semi-auto mode was observed. Also, blasters (presumably rifles) have stun setting, in addition to kill setting, as evidenced by TESB where Vader orders weapons set to stun before boarding Millenium Falcon. That does not necessarily imply different operating principle... only difference might be amount of energy fired at target.
