Not 100% sure but the only day they offer puclic service is wednesday, it's also the hardest day to visit it.

There are services held in St Peter's Basilica and masses held in many churches and basilica's around Rome

Yes, there is information about Mass schedule. See Catholic Traveller websyfor details.

Buongiorno, non so risponderti. prova a vedere sul sito del Vaticano.

The Vatican State has suspended the "skip the line" option. To skip the line at the Vatican Museum, you have just to book on line, on the official site: Vatican museums. As for the basilica, you have to queue. Of course, the earlier the best. The entrance to the church is free. If you want something "guided" you must go to the Vox Mundi desk, on the right side in the atrium. You can choose a guided tour (15 euro) or and audio guide (5 to 15 euro, depending by the options you choose) . The dome has a different ticket 8 euro by foot /10 euro with the elevator (and 320 steps anyway)

I was in Rome in November 2021. I visited St Peters and climbed the dome of St Peter's Basicila. I arrived early at the security queue. There was a short 10-15 minute wait. When I left 90 minutes later, it was taking over an hour to pass through security. My advice would be to arrive at St Peter's early.

We did a private tour and ended up in St. Peter's during 5 o'clock mass. What a stirring experience. Our tour guide, Gaia, was worth twice what we paid!!! I highly recommend private, if you can swing it.

No.