Thank you, Cruiser Bruce, for your helpful advice about transfer pickup times.
And, thank you also, Marazul, for the two links and your helpful suggestions. I have only been looking at 3rd party tour operators and hadn't thought to investigate tours directly with the sites themselves.
I am also now more informed about the issue concerning no tour access on Wednesday mornings at St. Peter's Basilica. The references to closures on many of these 3rd party tour websites didn't specify that they varied by weather. I have now learned that the Papal Audience is held in either St. Peter's Square, St. Peter's Basilica, or the Audience Hall, depending on seasonal conditions and the number of visitors. Hopefully, we will be lucky and the Papal Audience will be held in the Audience Hall/auditorium on the Wednesday we will be in Rome.
Again, thank you both. I really appreciate your helpful assistance!