I would like to know -
1. What is the meaning of "Dawah". Should I give dawah to a muslim or a non-muslim? And most importantly what does Qur'an/Hadith say about Dawah? Is it a Farz?
2. There are muslim organizations who are trying to establish a Islamic World through Khelafah. They are trying to revive Khelafah and they say this is a farz for every muslim. Now, which is most important(or first duty in importance) for a muslim- giving Dawah to a non-muslim or trying to establish Khelafah at present.
Or both are equally important.
3. Will I be asked about Dawah or duty for Khelafah in hereafter? Is it a sin if I don't do? Will I be punished? Tell me according to Qur'an and Hadith.

Thanks in advance.

Assalaam alaikum,
Masha Allah, it is such a noble cause to help people understand Islam better,May Allah bless you in your noble endeavors .
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Dawah - Sharing Islam (http://www.islamtomorrow.com/dawah/dawah1.asp)
Dawah is a word in Arabic that means "to invite" or "to offer to share." This is a very important part of being a Muslim and it can be somewhat difficult at times. Yet it is not impossible. The fact is that sharing Islam is a very simple concept. The difficulty comes in when you are trying to communicate the idea to others, especially when they have already been predisposed to believe in something else and to believe that Islam is something bad.

Keep in mind at all times that you are on a special mission to deliver a message of inviting people to worship Allah according to the way that He wants to be worshiped. You are to call them to know the truth and how to follow it. You do this with both your kind words and correct actions.

Your words are used in lectures, sermons, books, tapes and dialogs. These words help people to understand the truth of Islam.

Your actions are observed by others through your behavior and manners. You become the role model for what Islam is all about.

Both methods (dawah by words and actions) were used by the Prophet (peace and blessings be upon him) when delivering the message of Islam. He was the perfect example of what he was calling the people to do. Ayesah, may Allah be pleased with her, said that if you would like to see a living example of the Quran walking, then simply look to Muhammad, peace be upon him. His life was the best example of the noble teachings and principles set forth in the Quran.
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Islam Question and Answer - Which should come first – establishing the khilaafah or teaching the religion? (http://www.islam-qa.com/en/ref/5273/khalifa)

Wa alaikum salaam