4.2.2 (Jelly Bean)
Yes, the Nabi is an Android OS-powered tablet, but configured for children.
Well, it depends on what your needs are if you are searching for a tablet mainly for reading. The Nook has proprietary apps that are specific to that device that you might not find in a tablet with Android OS. However, you would have limited app choices, and an older Android OS built in with the Nook.
Android is a Linux OS
Yes, Openoffice was designed specifically for tablet use. It runs on the Android OS but may need an additional download of a file converter from the Android market place.
The Dell Streak smartphone/tablet already has Android OS (version 2.2, Froyo) on board.
Google Play should already be pre-loaded in an Android tablet, unless the OS onboard is older than Android 2.3 OS (Gingerbread).
The Barnes & Noble Nook Color uses a customized version of Android OS.
Because your Android OS version may be outdated. And there's no way to update it.
The LG X145, also called the LG L60, is a tablet from LG that uses Android OS.
If the file for flappy bird is compatible to be installed on the android OS, it can be moved between any android device.
Desktop MS Office is not available for Android OS. However, Microsoft has come out with Microsoft Office Mobile for all mobile operating systems, including Android OS.
Android Ice Cream Sandwich is next version of android OS. It will converge the formerly disparate phone and tablet versions of the OS. That means, it can work on both tabet PC and smartphone.