Vatican City Confusion!

Nope, for the city itself just walk in. It's indistinguishable from Rome as far as "borders" - just walk into St. Peters Square and you are in the nation of the Vatican.

I don't know about combined tickets, I don't think so. I could be wrong. St. Peter's Basilica is free (long line is for security check, there is no ticket needed), but you need a ticket to climb the dome and go to the roof. Well worth it.

For the Vatican Museum (this is the home of the Sistine Chapel as well as most of the famous art you hear is in the Vatican) I HIGHLY recommend an early access tour. This museum is extremely crowded and I find it frighteningly claustrophobic. The early tour lets you see it with fewer people. Plus it lets you into the Basilica without the security line, as you did security at the museum and there is direct entry for tours. I did one through Walks of Italy.

You can do the museum and St. Peters in a day, unless you can tolerate the museum for all day - there is plenty to see but the tour I did finished in the museum by 11 then went to the church. I suppose you could have a late lunch in the area then go to Castel San Angelo, but I'd be Vatican-ed out by this point. Technically possible though.

I found the church difficult to appreciate at noon but loved it first thing in the AM on another visit.

With 10 days I would go to the early tour of the museum one day, then some different day go to the Basilica early and do the dome climb as well as the church. Do San Angelo after one of the above.

is there a combined ticket for the museum, St Peter's Basilica,
Sistine and Castel Sant'Angelo, or would you buy them separately? Are
these all do-able in a day?

There are combined TOURS of the museums and basilica but as the church itself is free, you don't need a ticket for that. The official ticketing site for the Vatican is here:

http://www.museivaticani.va/content/museivaticani/en.html

And this is the page for their tours:
http://www.museivaticani.va/content/museivaticani/en/visita-i-musei/scegli-la-visita/visitatori-singoli.html

They offer an early-entrance tour of the museums...
https://biglietteriamusei.vatican.va/musei/tickets/do?action=gototipovisitapertag&tag=colazionemuseiingressoanticipato&weblang=EN

...and a 3-hour combo tour of basilica and museums (but not early entrance):
http://www.museivaticani.va/content/museivaticani/en/visita-i-musei/scegli-la-visita/musei-e-collezioni/musei-vaticani-e-basilica-di-san-pietro/visita-guidata-musei-e-basilica-s--pietro-per-singoli-e-gruppi-.html

Another very popular - albeit rather expensive - early entrance tour is Walks of Italy's small-group "Pristine Sistine" which also includes the basilica:
https://www.walksofitaly.com/vatican-tours/pristine-sistine-chapel-tour

A bonus of any museum+basilica combo tour is the ability to directly access St Peter's from a passageway reserved for tours. It saves a long walk outside between museums and church + another security queue.

But another good option? I see that you'll be in Rome on a Friday? You have the opportunity to see the museums during seasonal Friday late openings. While it doesn't include the basilica, this is also a very good time to visit the museum/Sistine with fewer bodies to contend with. You may chose to self tour or book one with a guide, and maybe visit the basilica before heading off to the museums:

https://biglietteriamusei.vatican.va/musei/tickets/do?action=booking&codiceLivelloVisita=17&step=1

Castel Sant'Angelo isn't part of the Vatican complex - although very nearby - so tickets must be purchased separately for that one. And yes, all 3 sites may be visited in one rather strenuous day (wear good walking shoes!!!).

http://www.ticketone.it/biglietti.html?affiliate=ITT&venueGroupId=17201&doc=venuePage&action=overview&fun=venue&language=en

As your trip is very soon, I'd hustle a little with your Vatican bookings. :O)

I'm in agreement with Kathy, take the official guided Friday evening tour. Not only is it less crowded, it frees up a day to use on other sites.

Not only is it less crowded, it frees up a day to use on other sites.

Exactly. This is a tremendous bonus when there's so much to see in Rome. It will not free up an entire day if you want to do the basilica and Castel Sant'Angelo before the museums, but it will free up enough time to add some other things with earlier closing hours.

We took the Friday night guided tour of the Vatican Museum during our visit this past June. I believe our entry was booked for 7:15 or 7:30 pm. I suggest that if you are considering the Friday night guided tour that you book at least an hour later than this. The crowds were still pretty thick at these entry times. I noticed that when we were leaving, it was a lot less crowded. The Sistine Chapel was also packed. We opted to visit the St. Peter's Basilica on a different day and that did not turn out that well. Twenty-nine years ago, when we first visited St. Peter's Basilica, I remember we waltzed right in (no security checkpoints at that time). I was not prepared for the lines to get into St. Peter's. We never made it in because, after waiting on line for 1/2 hour, we realized that we would never make it to our next scheduled event that day which was a tour of the Colosseum. There were plenty of ticket hawkers near the entrance of the Basilica who were selling tours which allowed you to "skip the line", but we opted not to go that route as we did not want a formal tour of the Basilica. If you're an early riser, I would probably opt for the Pristine Sistine experience which would allow you to see the Museum and the Basilica on the same day.

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There is the Scava tours which is Peter's tomb. It is under the main alter. You can purchase tickets from the Vacation website. There is also a video of the tour that you could access from the Vacatian's website. There is also a special Italian lunch served at the Vacatian museum. You do have to register in advance. Congrats! Have fun!

Wow, thank you all so much! This has really helped clear up some of the confusion I had. I will have a look at booking some tours, the evening tour sounds good, as does the Pristine Sistine tour. As we have so long in Rome, we probably won't be doing any of the major attractions on the same days such as the Colosseum and then the Vatican etc.

but do you need entry tickets to Vatican City itself

As was mentioned, No, but the only accessible areas are the square and the Basilica for free and the Museum/Sistine Chapel with a ticket. (Well, a couple other tour options as well) There is much more to the Vatican City, but off limits to the typical person.