To use the ebooks you purchased as apps, you'll need to extract the epub files from the apps, and then you should be able to read them on your Android device using an epub reader app.
You can find directions for extracting the epub at http://oreilly.com/ebooks/oreilly_iphone_tips.csp#extracting_a_pearl.
Once you have the epubs, you'll want to find an epub reader app for Android, like Aldiko, and then you should be able to read your ebooks.
I hope this helps.
Have a great day!