This addon tracks timers of many different world buffs and items. Starting off with Onyxia, WCB and Songflower, but many more are to be added until the list is complete.
When Horde or Alliance get the buff, a timer is put on your world map, and then broadcast to all your Guild members and raid members.
Same as above
This part works the same as (and should work together with) the addon https://www.curseforge.com/wow/addons/songbird