I'm curious as to why you think Joseph, or his parents had, at one time, been Quakers? Your reasons for thinking this may offer a clue as to where to look. You're looking at a lot of reading and research so I'd think it would be wise to have some realistic reason for thinking it a possibility.
However, here goes; there is no giant book that has all the Quaker info in it.....Hinshaw's Quaker Encyclopedia is probably the largest single compendium of Quaker information, but it contains, by no means, all Quaker data, and entire areas are not included...my own area of interest - Chester Co, PA....is not in Hinshaw. If you have no other info than the state of Pa, then your research would center there, and you need to so some background reading online, to get an understanding of the faith....and research into all the various meetings there might have been ca 1764, when you feel Edward was born. If Joseph was born a Quaker and was a member of a meeting, and then left to become a Baptist or Methodist circuit rider, then he would have been disowned by his meeting, and that would be in him meeting records. But, to determine this, you must discover the meeting that he belonged to, which is a big job with nothing to go on but a state.