Questions: Android native app testing

Hello Listers,
1. Are there any accessibility shortcomings that can be uncovered  by
using a switch access  method that cannot be discovered when using an
external keyboard with an Android device?

2. Sometimes  that an element is a heading or a button is conveyed via
android:contentDescription. As a result the item is not discoverable /
navigable using a selection via TalkBack's local context setting. This
in effect impairs the ability to use a documented accessibility
feature so is an accessibility failure directly  transgressing a
requirement for software accessibility IMO. However, "Don't include
the type of UI element in the content description" is merely noted as
a best practice at
http://developer.android.com/guide/topics/ui/accessibility/apps.html.

Thanks in advance for your thoughts / opinions on the above two  items.
Best regards,
Sailesh