If you don't want "hosted" SP functionality on 192.168.0.15, you can remove any saml:SP entries in authsources.
The frontpage federation page will show you what SP's and IDP's you are running on that instance.
Assuming you are using SAML 2.0 IdP, the REMOTE SP metadata files will need to be saved to saml20-sp-remote.php (In your case whatever app that is running on 192.168.0.2, convert its XML and save its metadata to that file)
You can set session times in the config.php. I don't usually bother with this as many of our vendors set their own SP session times.