Clarification on native watchOS apps [watchOS 3]

First, apologies for the fact that I am posting my question in the watchOS 2 forum. I recently purchased the watchOS 3 book and I had a doubt. Since I couldn’t a forum for watchOS3, I am posting here.

My question is to do with the fact that the tutorial book mentions the fact that developers can’t access a UI elements properties (ie. can’t read state) because applications are actually run on the connected iPhone. (Also because UI in a watch app are actually just representations of NSObjects). However, with watchOS 2, Apple said apps now run native to the watch. How do these two pieces of information contradict each other? Am I missing something?

Also, I am still unclear about which part of the watch app runs on the Watch and which part runs on the phone.

Lastly, how does Apple Watch manage to run without the iPhone (connected to the internet) if–as the book mentions–the extension is actually running on the phone?

Thank you for your time.
– Mayur