Short answers, pulled from the story.
Saint derives from the Latin sanctus, meaning holy or consecrated. It entered English through Old French seint and Middle English saint, retaining its meaning as a holy person. The synonymous English word hallow comes from the Old English halig, the same root as the word holy.
The Catholic canonization process has four major stages: an expert investigates the candidate's life, the report goes to the relevant diocesan bishop, the Dicastery for the Causes of Saints of the Holy See evaluates it, and the candidate may receive the title Venerable. Beatification with the title Blessed follows, and finally canonization requires proof of at least two miracles through the candidate's intercession. Pope John XV became the first pope to canonize a saint from outside his own diocese when he canonized Bishop Ulrich of Augsburg on the 3rd of January 993.
The Eastern Orthodox Church does not require miracles for sainthood, as Catholicism does; evidence of a virtuous life and prior local veneration suffices. The formal recognition is called glorification rather than canonization, and involves a service in which the saint receives a day on the liturgical calendar. The Church's position is that glorification does not create a saint but recognizes one who already was.
Most Protestant denominations use saint broadly to refer to all Christians, following Pauline New Testament usage. Evangelical Lutherans honor specific saints and allow their liturgical calendars to mark them, but prohibit prayers directed to saints on the grounds that saints are not mediators of redemption. Methodists honor and admire saints but do not venerate them, and the United Methodist Book of Discipline condemns the invocation of saints.
In Sunni Islam, saints were defined in the eighth century as people chosen by God and endowed with exceptional gifts including the ability to work miracles. Their veneration became one of the most widespread Sunni practices for more than a millennium. The Salafi movement in the twentieth century opposed these practices, drawing comparisons to the Protestant Reformation, though living saints with large followings continue to exist primarily within Sufi orders.
Alban Butler published Lives of the Saints in 1756, covering 1,486 saints. The latest revision, edited by Herbert Thurston and Donald Attwater, contains the lives of 2,565 saints. Robert Sarno, an official of the Dicastery for the Causes of Saints of the Holy See, has stated that it is impossible to give an exact total number of saints.