Did Paul (Saul) hear Jesus teach? I base this on his being approximately the same age and being taught by Gamaliel in Jerusalem during the time of Christ's ministry. A Jewish source mentioned that followers of specific Rabbis were sent out to listen to itinerant teachers to strengthen their understanding of Torah by comparing the teachings. I can't remember where I read he may have been an early follower but left when Christ's teachings became hard. To me this in part would explain his extreme reaction to the earliest Christians and why he was so aggressive in the discipline of the Christians.
To a certain extent you answer your own question. Saul (in his own testimony) claims an unassailable Jewish lineage(Eph 3:4-6). His devotion to the Jewish faith motivated him to repress what he perceived to be the ultimate heresy. The Bible records that he was present at the stoning of Stephen; this would have been sometime after the formation of the early Church. He would also have been a contemporary of the disciples themselves, therefore it is reasonable to assume that a teacher of Judaism would be careful to not respond to hearsay about Jesus's message and teachings.
He, in all probability, did hear Jesus firsthand, but as the Bible does not specifically state this, it remains a hypothetical question with the only answer being: unknown.