Do all Muslims speak Arabic, then?
No, but I think the majority of them can read the Qur'an in Arabic [Which is not the same as reading regular arabic/speaking it].
But no.
What is Ka'ba?
It is a black, cube shaped building that is the most sacred historical site in Islam, believed to have been built by Abraham and his son, Ishmael. Furthermore, The Ka'aba is the location to which Muslims pray towards, no matter where they are on Earth. Lastly, it is the site of Hajj. Oh, and it has a Mosque built around it.
What do you have to give to the church(a percentage of income, labor, etc.)?
Nothing. Although we are required to pay Zakat, the Quran makes no specific mention of who it goes to and how it is distributed -- only that alms reach the poor. Many people do, though, contribute funds towards their mosque's to enrich their community and also give money to mosque's to carry out the act of giving Zakat to others.
But to the mosque itself, we owe nothing. A mosque is a community run establishment, so it doesn't really rule over anything.
Why do some Muslims wear turbans?
Some Muslims wear turbans because it is a confirmed Sunnah, or a thing that the Prophet did. It also has roots in many cultures in the regions, so that is also why many people wear it.
But it isn't only Muslims [just clearing that up] -- Many Indians, Hindu or Sikh, also wear Turbans they call Pagri, and many of them are quite commonly mistaken to be Arab or Muslim. In the USA, the majority of the Turban wearers you see are probably not actually Muslim.
Is hafiz a requirement, or just something that people do voluntarily?
It is no requirement. You need portions of the Qur'an memorized to do prayer, but there is no requirement to memorize the entire thing. It is more of a voluntary thing that brings a lot of respect and pride to those who do it.
I will say that some parents make their children Hafiz.
The tradition/idea behind becoming a Hafiz is that in the Arabia of 600AD, there were not many access to resources, nor were there many literate people. So to give the message of the Qur'an following the Prophet's death, the idea was to have the entire recitation memorized, as it was the best way to spread the message [Everyone spoke arabic, and it isn't costly to speak]. Aside from tradition, a Hafiz can make a really good Imam because he can recite any portion of the Quran with ease during a prayer, and tell others about his faith using the best source possible.
What is Islam's policy on conversion? Do you have to actively try and convert people, like going on missions and whatnot?
You aren't forced to actively try to convert people, but you can't live in a box either. What I mean to say, it isn't your job to convert people, but you can't be very pious and have nobody know that you are a Muslim. For anyone that meets you, if they show interest or ask a question, it is better to give them the best understanding of Islam that you can without violating them in any way.
