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Speaking as a member of one of the Churches of Christ, I can shed some light on this matter. I cannot supply any authoritative sources (other than Scripture, and in many cases only the silence of the Scriptures), because the Churches of Christ do not have anyone who is authorized to speak for all of them. (That's kind of the point.)
The Churches of Christ have no formal organization above the level of the local congregation, because the Scriptures do not describe any. The affairs of each congregation are overseen by a plurality of elders (appointed in accordance with Scripture) who are members of that particular congregation.
Congregations of the Churches of Christ believe that the baptism (of a believer in Jesus Christ as the Son of God) is the point at which salvation is obtained. This is how we understand the verses which discuss both baptism and salvation.
Congregations of the Churches of Christ partake of communion on every first day of the week. This appears to be what the early church did (Acts 20:7).
Free-will offerings by the membership (generally collected during the formal worship) are the sole means of raising funds. The Scriptures command this of all Christians who are able, and do not speak of any other source of funds. Congregations may (and often do) provide support to other congregations, but this is entirely at the discretion of the congregation from which these funds come.
Most congregations of the Churches of Christ practice congregational singing as their sole form of music in worship. (Again, there are no scriptural examples of any other form of music being used by the early church.)
After that, different congregations have different practices and teachings, but they are generally on the level of "agree-to-disagree".
I cannot speak for the other two religious bodies, as I have never attended their services, participated in any of their other activities, or read their literature.