As long as Aryeh Leib's mother was Jewish, then he would automatically be a Cohen. It is standard practice to put "haCohen" only after the father's name.
I BELIEVE, but am not 100% sure, that the "Shochet u'Vodek" refers to his father.
As to the title "Rev", meaning "Reverend". This is a title that my own father -- who was also a Shochet -- had, as did the other Shochtim [that's the plural] in the town. It means that the person is a religious functionary in the community, but not a rabbi. It was a title that was also used, for example, by cantors.
Brooklyn, New York, USA