We should always be praying. Advent is more focused o the theme of awaiting the Messiah. We remember the coming of Christ in the past (Preparing for the celebration of Christmas), and also prepare for the coming of Christ at the Final Judgement.
Fasting is not required during Advent.
celebrate his birth by praying, singing and other activites...
They can and do eat whatever they wish to eat during Advent.
The Gloria is not said at Mass during Advent and Lent.
because hyms hymns are prayers, and you pray a lot during advent.
The Roman Catholic church has a tradition of lighting Advent Candles during the four weeks of Advent.
Advent is a time of preparation for the coming of Christ at Christmas.
The primary thing that you have to do during Advent is to prepare for Christmas, you do this through confession, Mass, and prayer.
In the Traditional Roman Rite the Alleluia is used on Sundays of Advent along with the Gradual, but if the Mass from the Sunday is used during the week the Alleluia is omitted. It is not omitted during Advent in the Divine Office.
I am not sure what you mean by Advent Saint. There are hundreds of saints who have a feast day during Advent, including St. Nicholas of Myra. However, if any saint would be named as the Advent Saint it would be St. John the Baptist as the Gospels during Advent speak of him preparing the way for the Lord.
There are hundreds of saints who have feast days during Advent. It is just a coincidence.