These are all good ideas. None of them are currently possible as-is, but I think they're all possible via hacks. It would be great if you could open new tickets for them on the Google Code site:
http://code.google.com/p/slimstat/
Having said that, a couple of these are relatively easy hacks, namely:
> --Purge hit and visit data from prior months, but retain the monthly
> summary report.
SlimStat caches the results of previous months' and days' queries, so the data from any queries you have previously run will still show up in the front end. You can delete previous data from the database like so:
DELETE * FROM slimstat_hits WHERE yr=2009 AND mo=10;
DELETE * FROM slimstat_visits WHERE start_yr=2009 AND start_mo=10;
> --Alternatively, anonymize IP numbers, maybe via a salted one-way hash
> or something like that.
Change line 36 of stats_include.php from this:
$data['remote_ip'] = $this->_determine_remote_ip();
To this:
$data['remote_ip'] = sha1( $this->_determine_remote_ip() );
Hope that helps.
Stephen