For future generations, the way to configure backups is described here: Configure Backups on your LEM Appliance - SolarWinds Worldwide, LLC. Help and Support
The answer is "It depends," and the differences are described here: Live Data Storage Retention in LEM - SolarWinds Worldwide, LLC. Help and Support
To get 100 days guaranteed of raw syslog storage, you'd probably want to setup the syslog backups to your own server, they'll be tar.gz'd from the LEM.