Question 1:
Why is Jesus called "Jesus" and not Immanuel, since according to Matthew 1:23, His name was to be called Immanuel?
(The virgin will be with child...and they will call his name Immanuel - which means "God with us". - Matthew 1:23)

Response:
Understanding the practice of the culture at Jesus' time clears this question up right away. People were called not just by a name but by titles, as well. Jesus' full name would have been "Jesus ben Jacob", meaning "Jesus, son of Jacob" (Jacob was Jesus' stepfather). 

But titles were often attached to people to help define their roles and significance. An example of a person with an extreme title who lived near the time of Christ is Galarius Ceasar. Read the following prayer he wrote and you will understand the significance placed on titles:

Galarius Caesar’s Prayer in 300 AD as recorded by Eusebius
The emperor Caesar Galarius, Villiniois Maximanous, Invictous Augusts, Pontificus Maximus, Germanics Maximus, Egypticus Maximus, Phobecus Maximus twice, Carpticnes Maximus eight times, Armenicus Maximus, Medicus Maximus, Adeabendicis Maximus, Holder of Tribunal Authority for the twentieth time, Emperor for the nineteenth, Counsel for the eighth Pater Patrea Pro Counsel...and THAT'S just to help identify WHO you are talking to!

In the Matthew 1 passage, Jesus (that's his name) has the Old Testament title of Immanuel applied to Him. The title refers to Jesus' role, the One who brings God to us, Immanuel, God with us.