Possibly. He has stated that he may write more novels set in Alagaesia, including a direct continuation of the Inheritance Cycle.
As of December 2012, Christopher Paolini hasn't announced any new books to be released.
He wrote the famous Inheritance cycle series of books.
Eragon
Yes, he has a sister named Angela Paolini. Christopher has stated that she was the inspiration for Angela the herbalist in his series.
In Christopher Paolini's books, the elves are known as the "Elves" or the "Sylvans." They are a magical and long-lived race with a deep connection to nature and possess advanced knowledge and skills in magic and swordsmanship.
It is not said in any of the books, but Christopher Paolini said that the last dragon egg is green.
Murtagh is a character from the Inheritance cycle, not Harry Potter. Christopher Paolini has not released his fourth and final book yet, so there is not an answer to your question at this point.
Yes, he has a sister named Angela Paolini. Christopher has stated that she was the inspiration for Angela the herbalist in his series.
Yes, before becoming a full-time author, Christopher Paolini worked as a professional musician and also held temporary jobs such as driving delivery trucks and as a sales clerk.
There is only the first one called " Eragon".
Yes, there are many fantasy books that revolve around elves. Some popular examples include "Lord of the Rings" by J.R.R. Tolkien, "The Inheritance Cycle" by Christopher Paolini, and "The Dark Elf Trilogy" by R.A. Salvatore. Elves are often depicted as a magical and long-lived race in these books.
He has not. See related link for his website.