I already replied to the first question here - http://www.telerik.com/forums/what-markup-is-planned-for-ui-elements
On your second question -
Secondly, for those of us new to developing Native apps for iOS and Android, what learning materials do you recommend to help using NativeScript? I doubt we need to become expert in Objective-C/Java and iOS/Android Operating System, but what should a NS developer become proficient at?
Yes - you are correct - a developer using NativeScript will not need to know iOS/Android or Windows specifics in order to create applications for them. The UI abstractions implemented in NativeScript should be enough to create the application you want.
When we are building the framework we have two important principals in mind. First - keep it simple and straightforward and second - try to reuse as much as possible the skill set of the web developer. Which means that we will try to support as much existing JS libraries as possible and we will try to introduce minimal new concepts so that the getting started experience with NativeScript is very smooth.
Have you been able to play already with the framework?
I hope this helps,