There is an inconsistency regarding the value of indexStats.trace for not tracing anything. The source mentions both "none" and "off", but the latter seems to be the dominant one. I corrected the comment in revision 1307392, and I also removed two TODOs.
Tracing and logging is completely separate, yes.
The changes look good to me, +1 to commit.
There is one trick that may be useful in rare cases, since the properties are static, and that is to generate a stack trace and look for the daemon thread to determine if the daemon is active or not. I don't think it belongs in the docs - hopefully people will find this comment instead