Not long. Male breast reduction is a surprisingly well tolerated surgery without need for heavy duty analgesics. Most patients are up and about within hours after surgery and back to work quickly. Of course pain thresholds vary but this surgery will not keep the average male down for long.
Variable. If you have liposuction or removal of excess skin and breast tissue, you would be sore for a few days. Likely, you'd want to take a few days off of work. You should be fully healed within four weeks.
Depends. This depends on the extent of surgery and what it is you actually do. Most of the people that I have operated on for this condition are sore for a day or two, but are then able to return to work. As any other surgery they have to make sure they don't get the wound dirty or cause bleeding or get an infection. Most of the wounds are clearly healed by 4 to 6 weeks.