Hi Gudu,
In IS Admin page, Under “Settings” tab (left side), click “Logging” - here you can set all the loggers details inculding “Service logger” details.
and for checking the service logs - click “Service” tab under section “Logs”.
Re. your Service Usage information query - As other members said- in wMRoot package we have inbuilt service wm.server.query:getServiceStats which actually gets all this service usage information for this section. But unfortunately the code is hidden here 
Thanks,
Mohit K
#Integration-Server-and-ESB#webMethods