No
The Vatican houses the head of the Roman Catholic Church and all of his advisors so I would venture to say that it is a primarily Catholic community.
There is only one religion practiced in Vatican City, home to the Pope, and that is Catholicism.
All, except the Vatican City, Malta and the Philippines (Malta has already approved divorce in a referendum and will be legalizing divorce anytime soon. That leaves Vatican and the Philippines the countries NOT allowing divorce)
No. The only religion in the Vatican is (Roman) Catholic-Christianity. However, there are many people of different religions or none at all that visit the Vatican for history-learning purposes only and there may be (on occasion) a leader of a different religion might meet with the pope; though its quite rare as the current Pope only meets with Catholics and other Christians not part of the Catholic Church. The Vatican has an official religion and that is Catholicism within Christianity. In a way (in some respect) the Vatican is the official "headquarters" of Catholicism and not any other religion.
As of early 2014, no miracles have been approved by the Vatican as having happened in Medjugorje.
That the emporer made Christianity one of the few religions approved
Absolutely. Being the home of The Pope and the Vatican, you'd expect it. The major religions in Italy are Christianity (Catholicism), which over 80% of the population follow.
Vatican City is all that remains of the Papal States.
Vatican City is all that remains of the Papal States.
Yes, in Vatican State. However, all religions except Catholicism are prohibited from practicing there. The only churches are Catholic. Non-Catholics are welcome to visit, however.
All the bishops in the world met in the Vatican, at St. Peter's Basilica off and on for three years beginning in 1962 through 1965. They discussed and vote on various documents, which then had to be approved by the reigning Pope, and were published. You can see the documents at the link below, and pictures of the Council at the second link.
Her apparitions continue to this day. The most recent apparition to be approved as authentic by the Vatican was Our Lady at Akita from 1973 to 1979. However, the apparitions of Our Lady at Medugorje have been happening since June 24, 1981 and have continued with the most recent being August 2, 2010. This apparition is not currently approved by the Vatican, but it is under investigation.