Hi Andrew,
You have a great question. Typically items like these can be found in the SDK. However, there doesn't really appear to be great documentation out there for this information. Realistically, there are only three different ownership types of a record, User, Team, Organization. However the SDK, provides more values as documented here under "Entity Ownership":
msdn.microsoft.com/.../gg309396.aspx
The values for the ownership types are found here:
msdn.microsoft.com/.../microsoft.xrm.sdk.metadata.ownershiptypes.aspx
However due to serialization, the value shows differently in the database.
In regards to your second question regarding users being able to update the campaign if a team owns it, a team will have a Security Role as well. The permissions of a user are additive. Meaning, if user only has user level rights on campaign and the team has user level rights on campaign and that user is a member of the team, that user would have permissions to anything that is owned by the team.
Let me know if this doesn't answer your question.