Q. Where can I find statistical data information such as demographics, surveys and ethnographies on denominations, churches?

Here are suggested databases you may find helpful. 

World Christian Database (Fuller credential required for  access)

The World Christian Database (WCD) provides comprehensive statistical information on world religions, Christian denominations, and people groups. Extensive data are available on over 9,000 Christian denominations, 13,000 ethnolinguistic peoples, as well as data on 5,000 cities, 3,000 provinces and 234 countries.

World Religion Database (Fuller Credential required for access)

The World Religion Database (WRD) contains detailed statistics on religious affiliation for every country of the world. It provides source material, including censuses and surveys, as well as best estimates for every religion to offer a definitive picture of international religious demography. It also offers best estimates at multiple dates for each of the world’s religions for the period 1900 to 2050.  

Additional Databases (mostly open access resources)

• Association of Religion Data Archives The ARDA provides American and international, religion data for educators, journalists, religious congregations and researchers.
• Pew Research Center - Religion & Public Life "Pew Research Center is a nonpartisan fact tank that informs the public about the issues, attitudes and trends shaping the world. It conducts public opinion polling, demographic research, media content analysis and other empirical social science research. Pew Research Center does not take policy positions. It is a subsidiary of The Pew Charitable Trusts."
• World Values Survey The series is designed to enable a cross national comparison of values and norms on a wide variety of topics and to monitor changes in values and attitudes across the globe. A variety of questions on religion and morality were included. This longitudinal survey currently covers the years 1981-2014 in seven waves.

• Data.gov The home of the U.S. government's open data. Here you will find data, tools, and resources to conduct research, develop web and mobile applications, design data visualizations, and more.
• U. S. Census Bureau The Census Bureau's mission is to serve as the leading source of quality data about the nation's people and economy.
• Fed Stats Access to statistics and information produced by more than 100 U.S. Federal Government agencies