Re: Kids books and apps for tablet (non- iPad).
I don't know about on android market place, the boys tablets came with the amazon app store and we have stuck with that because there were plenty of apps available. They are all android apps though so they would run on any android tablet (my boys have polaroid tablets). I believe it is fairly simple to download the amazon marketplace app and attach it to your existing amazon account. You can then either lock it on the tablet so your child cannot order apps at all (you would need a pin number to order from the tablet) and you could order from your computer on your own amazon account which I do all of the time and send them directly to my boys or you could just tell them to only download free apps.
The app I mentioned is called Pocket Penguins and it is a free app. Tharen isn't into it but Kearnan enjoys it.