Muslims in the world are around 1600 millions as of October 2009 per Pew Forum study. Nothing in Islam is called Islamic church.
The Headquarters of OIC is located in Jeddah, Saudi Arabia.
Eleven until next year when the twelve team joins.
loads of members worldwide in politicians
I think it is three. Mainly they are two: 1. Eid Al-Fitr ( lasts for 3 consecutive days).2. Eid Al-Adha (lasts for 4 consecutive days).