Did Paul's wife travel with him and then he became a widower? Does Pharisee of Pharisees mean that his family goes back several generations, father, grandfather, etc. of Pharisees? What does Roman by birthright mean?
Any speculation about Paul's wife (or lack thereof) is just that, speculation. Unless there is some authoritative extra Biblical source, we know only that he is, at the time of his writing of 1 Corinthians, unmarried and the inference is that he has never been married (But each man has his own gift from God. 1 Cor. 7:7).
As for 'Pharisee of the Pharisees', it is emphasizing that he is/was the "best of the best" as can be seen in the context. Paul did not brag but did not exhibit false modesty either.
Finally, pertaining to his Roman citizenship, one could be born a citizen, purchase his citizenship or earn his citizenship through some service to Rome. Paul was born a citizen because his father was a citizen. The speculation is that his father performed some service for Rome but that is only speculation.
I've come late to this question but I will offer a new perspective on Paul's parentage. Acts 23:6 does not use the term "Pharisee of Pharisees" but specifically "the son/child (υἱὸς) of a Pharisee." A few typical translations:
- KJV: I am a Pharisee, the son of a Pharisee
- RSV: I am a Pharisee, a son of Pharisees
- NIV: I am a Pharisee, descended from Pharisees
- YLT I am a Pharisee -- son of a Pharisee
I see no reason to presume this means something like "best of the best." In context - trying to gain sympathy from the Pharisees on the council as opposed to the Sadducees - it is more likely that he is displaying his ancestral credentials, not boasting that is a really good Pharisee. (But he is also emphasizing his affinity with the Pharisees against the Sadducees.) A similar construction is used in Phil. 3:5 when Paul says he is "a Hebrew born of Hebrews," in other words not a recent convert. At the same time we should be aware that the quote from Paul about his being a "son of a Pharisee" is not his own writing but a report by Luke, probably heard at second-hand.
So, if Acts is accurate in quoting Paul as saying "I am a Pharisee, a son of a Pharisee," we can understand that this is a statement about his family's tradition. He is not a newcomer to the movement, but he has inherited the tradition from his family as well as his teachers.