As to your questions:
1. Pinch and Zoom will work in most of the platforms that support multitouch gestures (at the time of writing - iOS 4+, Android 4+, WindowsPhone 8).
2. For Android the supported version is 4.2 +. All 4.0.x versions of Android the browser engine does not render the elements' transitioning properly, even the Hardware Acceleration is switched on, thus the poor performance of the Pinch and Zoom functionality. Unfortunately, there is not much the Kendo team or the AppBuilder team can do about this.
3. The issue sits in the Android's WebView version and not in the device itself.
Please, let us know if further questions occur.
Anton Dobrev ,