He was a moderately successful literary agent out of New York who came from England. He appears to be of middle-age, possibly mid-to-late-40s.
Every time Crowley has left his vessel briefly, his vessel appeared lifeless and motionless. After Castiel was afflicted with the Attack Dog Spell, he stabbed this body repeatedly with an angel blade after Crowley had vacated him to avoid Castiel's attack. This would indicate the vessel's death if it had not been the case by that point. After ensuring his demons had secured the vessel, Crowley later returned to it.
Crowley briefly left this vessel again in order to possess Castiel, who was trapped inside his own body by Lucifer. Crowley somehow managed to carve a message on his vessel's forehead, begging Sam and Dean to help him. After being freed from Castiel/Lucifer's body, Crowley returned to his own.