It has not been mentioned anywhere how the princesses came to be.
So far there has been no mention of how Luna and Celestia came to be.
Princess Luna became jealous of Princess Celestia and tried to take full control of Equestria and bring everlasting night. Celestia was forced to banish her to prevent this.
No. From the first episode: "...the eldest used her unicorn powers to raise the sun at dawn; the younger brought out the moon to begin the night."; this indicates that Luna, the one who controls the moon, is the younger of the two princesses.
Not that we know of. Luna is her only known sibling.
Right around $12.
Like her sister Princess Luna, Princess Celestia is what the fans call an alicorn. Offically the princesses are all three races at once, equally an earth pony, pegasus, and a unicorn.
Most likely not, based off of the fact that Twilight is only Celestia's student, and never considered anything more. Since Luna is Celestia's sister that would mean since Twilight isn't shown to be related to Celestia, she can't be related to Luna. She is however related to Shining Armour. He is her brother.
So far there has been no mention of the parents or any the mention of the origin of Celestia and Luna.
because she is a queen and she came first in a eqestria.
Yes, Princess Celestia, Luna, and Cadence will get their magic back since the main 6 defeated Tirek and have been rainbowfied to help Equestria receive their magic back. If you want to watch it you can on Youtube or Dailymotion
Because her sister, Celestia, raises the sun. We're not given any specific information about the how, why and when, but Luna's coat color and overall affiliation for night time would hint that it was always her destiny to be the Princess of the Night, just as her sisters' was to be the Princess of the Sun.
the elements were destroyed remember! this means that she had to recreate them using twilight sparkle an all her friends its the friendship that is the elements also its kindof for entertainment purposes too!