First and foremost, you do not need to bother about entrance documents. The Vatican does not need a visa to enter. While Italy is a signatory to the Schengen Area Agreement, the Vatican City is not; yet, since the boundaries are so porous (and sometimes non-existent), many people believe the Vatican to be a de facto Schengen Area state. That is made feasible by the state-within-a-state arrangement. The argument is that visiting the Vatican is as simple as visiting any other area of Rome. Nobody asks for paperwork. The Swiss Guard stationed at the gate is only for security purposes. They don't deal with immigration because there isn't one.
Aside from the paperwork, there are a few more things you should be aware of. For one thing, the Vatican City is home to the world's biggest museum. It would take around 5 hours to view all of the galleries inside the Vatican Museum. Michelangelo's ceiling fresco in the Sistine Chapel is the crown treasure. It's a great work of art, and no photograph can do it justice. It is a must-see attraction in the Holy See.
You may see the Pope on any given Sunday at noon when he comes out to bless the gathering. He stays for approximately 30 minutes, delivers a speech, and then goes. In addition, the Pope has a public audience every Wednesday. These meetups might run anything from 30 minutes to two hours. As you may understand, you must arrive quite early.
While you may take a self-guided walk of the property, joining a tour is the best way to explore Vatican City. You may learn about the museums' history and art, as well as many intriguing information about the Holy See itself. Because there aren't many sites exposed to the public, you may go from one location to another and take in the views.
There are certain limitations as well. For starters, you should dress accordingly. You must be 'decent': after all, this is a very sacred site. If you are a woman, you must cover your head while entering the Basilica of St. Peter, and neither gender is permitted to wear shorts. Your hands and legs must always be covered.
At the same time, you are not permitted to use your mobile phone or camera within the Basilica or the Museum. Flash photography is highly banned, and if a Swiss guard catches you doing it, you will be taken off the site. It is preferable if you follow this guideline and catch the lovely art with your eyes and thoughts. Photos may be purchased from souvenir stores.
As you may have suspected, there are no lodging alternatives in Vatican City. However, there are several hotels in the vicinity of the Vatican. There is no alcohol on the grounds, save for the wine used during communion, however food is offered. There are a few restaurants, a pizza establishment, and other amenities. You will not go hungry, I guarantee it.
The Vatican City is a sacred site, yet it also houses one of the world's biggest museums. Even if you are not devout, or even if you are not religious at all, you may enjoy its beauty and history. It would be a shame to visit Rome and not see St. Peter's Square or the Basilica.