For the most part, a blue dot on a chat thread means it has an unread message. Having that blue dot on every single new thread of every new friend that just got added increases the cognitive load.

Can you view a Facebook story without them knowing?

Heres how you do this: Open a story on Facebook, then hold your finger on either the left or right side of the screen and swipe left or right without releasing the finger. This allows you to see the Facebook stories to the left and right without them knowing.

Can you view someones story without them knowing?

If you turn on Airplane mode and turn off your WiFi (on an iPhone, at least), you can then watch the persons entire story without them knowing.