Can the WiFi network I m connected to see what I m watching on Netflix?

Every YouTube video has a unique URL so they can simply past it into another browser to see what the video is.

Netflix is different. They can see you are on Netflix - but whatever show or movie you watch is not a separate address so there is no easy way for them to see what you were watching.

What they can see is that a lot of data is going between their router and a particular IP Address.

yes

YES, they can easily see what you are connected to.
They will be monitoring and watching for all connections.

As long as your on the same network its possible to track what you're doing.

Nope. Unless they get on your device than yes they can.