There are two interpretations of your question.
To physically enter a church building for a Catholic Wedding: Simply arrive early and sit on the left side if you are with the bride or the right side if you are with the groom. If you are confused, just ask.
To enter the church in the spiritual manner: First, any baptized Christian can become the spouse of a Catholic. You do not have to become a Catholic to marry one. However, if you are interested in joining the Church, you are very much most welcome. Inquire with a local Priest about RCIA. This is a series of evening classes that typically begins in September and goes until the following Easter.
In a Catholic Church.
No, a Catholic wedding is a sacrament and, by canon law, must be celebrated in a Church that has been consecrated by a Catholic Bishop.
St Vincent Catholic Church
Only if one party is Catholic.
Yes
The question, as asked, makes no sense. The Pope is the Vicar of Christ and universal bishop of the Catholic Church. In a certain sense he is the Catholic Church as he, in his person, represents Our Blessed Lord, Jesus Christ, Whose Mystical Body IS the Catholic Church.
Yes, as long as she does not choose a Catholic Church. She will have to find a church that will perform an interdenominational wedding of divorced persons. The Catholic Church will not.
Assuming no divorce has taken place, which would require an annulment, yes, if you have changed from Orthodox to Catholic it would be possible to renew your wedding vows in a Catholic Church. There would be no need for a full blown wedding, however, as the Catholic Church does accept the sacraments of the Orthodox Church as valid.
Yes, not only must they take a class, but the Catholic must receive special permission (which is not always given) from the Bishop to have a wedding outside of a Catholic Church. Even if it is outside a Catholic Church, the wedding must still be witnessed by a Catholic priest (deacon, or bishop) or it is not valid.
Only Catholic weddings may be performed in a Catholic Church without special permission from the Bishop of that diocese.
The Catholic wedding vows have never included the promise to obey. This addition to the wedding vows was added to the ceremony by King Henry 8 when he separated England from the Catholic Church and declared himself head of the Church of England. In the Catholic vows, both parties promise "to love and to cherish."
Well, since the Catholic Church is not involved in the wedding, one would best address this question to a minister in the Church of England. The Catholic Stance on this wedding is that the divorced Catholic would be committing adultery as the Sacrament of Marriage is a commitment until death. See the link below for more of a detailed explanation.