I started using the Zondervan "Church and Nonprofit Tax & Financial Guide" by Dan Busby a few years back. I just ordered the 2011 edition for 2010 tax returns and received it from Amazon. I recommend that every US church own this book as a resource for their church treasurer, administrator, and/or bookkeeper.
This tip sheet from the IRS will assist you in determining the tests that the IRS considers regarding determining if workers are independent contractors or employees.
Internal Revenue Service website for charities and religious organizations.