This is Pulse. It's not included anymore. Think ComiXology got pulled too (it was included in 1st gens FYI).
http://www.amazon.com/Alphonso-Labs-...keywords=Pulse
Oh your KF, the Appstore is within the Apps tab. Here is the website:
http://www.amazon.com/mobile-apps/b/...ode=2350149011
Always hit the Sync button when you download something and it doesn't show up instantly, shouldn't be taking hours.
Have you read the manual that's pre-loaded? That might help a bit.