"Which church did he start?"
There is no evidence that he started any church. He was an apostle to the Jews and Rome was a gentile church with a problem with the Jews. Paul's letter is a criticism of them for their arrogant attitude toward the Jews, so if Peter started the church or was its first Bishop, he wasn't doing a very good job in Paul's eyes. Paul does not even mention him in the letter.
I just finished going through the entire first volume of the earliest church fathers up to Irenaeus and there is no mention at all of any perpetual virginity.
That's intriguing.
There was plenty of the mention of Mary being a virgin and the fulfillment of the Isaiah prophecy, but not once did anyone go beyond that simple fact.
Take that up with XZins. I go to Petrine Church often.