Each solution within the Adobe Experience Cloud has user permissions management allowing you to control who within your organization can make changes. If you'd like a more specific answer, please post a similar question in that solution's community.
I'm not sure what SVN is as it relates to Adobe. Can you please clarify?
Unfortunately, each of the Experience Cloud solutions has different code bases and deployment methods at this time. That means, each solution will have various ways of using code control systems.
For more info, I'd reccomend posting in each of the solution specific forums.