File

To get the user name who modified a file:

http://stackoverflow.com/questions/11660235/find-out-usernamewho-modified-file-in-c-sharp

To create a new user account:

public string CreateUserAccount(string ldapPath, string userName,
    string userPassword)
{
    try
    {
        string oGUID = string.Empty;
        string connectionPrefix = "LDAP://" + ldapPath;
        DirectoryEntry dirEntry = new DirectoryEntry(connectionPrefix);
        DirectoryEntry newUser = dirEntry.Children.Add
            ("CN=" + userName, "user");
        newUser.Properties["samAccountName"].Value = userName;
        newUser.CommitChanges();
        oGUID = newUser.Guid.ToString();

        newUser.Invoke("SetPassword", new object[] { userPassword });
        newUser.CommitChanges();
        dirEntry.Close();
        newUser.Close();
    }
    catch (System.DirectoryServices.DirectoryServicesCOMException E)
    {
        //DoSomethingwith --> E.Message.ToString();

    }
    return oGUID;
}

Reference:
http://www.codeproject.com/Articles/18102/Howto-Almost-Everything-In-Active-Directory-via-C#40

To view previous version of File:

FileVersionInfo vi = FileVersionInfo.GetVersionInfo(YourFileName);

string showVersion = vi.FileVersion;