Hello David,
I am assuming that you are using the Delphi library. Please correct me, if this is wrong.
You are right about the locked log file. It is currently not possible to copy a log file when it's opened by the Delphi library. With the Java and .NET libraries you should have no problems though. The good news is that we already fixed this and the fix will be included in the upcoming 1.1 update (which will be released around August).
About the changing log files: The easiest way to create different log files for each day is to just change the Connections property daily. So you could just use (assuming Delphi again):
Si.Connections := 'file(filename=c:\2005-07-05.sil)';
[...]
Si.Connections := 'file(filename=c:\2005-07-06.sil)';
That way, you will not lose any log entries and you will get a log file for each day. We will consider an automatic log rotate feature for a future release.