Assuming that stormtroopers are 1.9 meters high in armor, we have 0.25 cubic meters of concrete blasted by Han's shot. According to some sorces, concrete crumbles like sugar if temperature is higher than 1000 ° C. Heat capacity of concrete is 0.75 for stone or 0.96 kJ/kg K for light concrete according to this page, and its density is 2400 kg/m^3 for normal and 1750 kg/m^3 for lightweight concrete.
Therefore we have 437.5 or 600 kg of concrete blasted (I will assume that concrete crumbled; big piece falling might be from above hole). This gives us 420 to 576 GJ for that shot, high end. On the other hand, picture below shows hole of 0.00536 m^3 by shot from blaster rifle (obviously set on kill). That gives us 9.65 MJ shots, more in line with other Star Wars firepower examples (actually, given firepower of Imperial armored vehicles, and fact that every other usage of blasters promptly contradicts it, Tatooine example can be disregarded alltogether).
Very short - rarely seen used at distance of more than dozen meters.
Unknown. Presumably kill and stun only - being military weapon, blasters must have kill setting, and in TESB Vader orders weapons to be set to stun. While he was probably referring to rifles, we can assume that hand blasters also have that option.
