Information about Apple Security Updates can be found on https://support.apple.com/en-us/HT201222.
To get timely information about Apple Security Updates you can subscribe to the Security Announce mailing list via https://lists.apple.com/mailman/listinfo/security-announce.
Apple Service Programs
To find out whether your device is covered by a special repair and service program you can visit https://support.apple.com/service-programs.
Manuals for Apple products are available from https://support.apple.com/en_US/manuals
Apple Service Status
Apple maintains a page that summaries the status of its services under https://www.apple.com/support/systemstatus/