Threads: Tagging everyone in a thread doesn't work / Can new members see threads automatically?

Hi - two questions actually that I can't solve. 

1) Tagging @everyone in a thread doesn't work for members who haven't already joined the thread. The Discord Threads page says that it is supposed to. 

2) New members don't automatically see threads. Is there no way to make this automatic rather than them having to manually choose to view them?