New to LibreOffice on iMac OS el capitan. Used to use MS 2008. I can open my documents but have to tell them to use LO each time is there a way of making my documents automatically open in LibreOffice? Thanks

Also is there a sort of “manual” (albeit virtual or physical) of Libre Office?

Maybe http://www.imore.com/how-change-default-apps-os-x will help

And for documentation, start with https://www.libreoffice.org/get-help/documentation/