twerppoet said:Two possibilities, well maybe three.
First and most likely is iBooks. There is a category in the iBooks Store for Textbooks. The book in this category are created with iBooks Author for OS X, and have special features and formatting optimized for media rich textbooks. There are several free books, and you can download samples from most titles. Give them a try.
Apple - Education - iBooks Textbooks for iPad
It is also possible to use e-textbooks purchased from Amazon. The Kindle app on the iPad has recently been enhanced to handle these. You'll have to do your own research on those, as I haven't had reason to look into it myself. I don't know what features, beyond basic ebooks, Amazon is offering.
The third possibility is an app as a book. These would be found in the App Store under Education or Books or the relevant subject. Essentially these are app, but with book-like content, often enhanced in some way. There are several very powerful books, like Gray's Anatomy, for specific fields.
I've probably missed something, but I hope that helps.
twerppoet said:Oh. That I can't help you with. Not all content is available in all countries. Books seem to be a special problem, probably due to copyright issues.
All I can suggest is that you get a second iTunes account in the U.S. (or other country with a better selection). I've never done it myself, but here are the instructions as far as I can determine.
Creating an iTunes Store, App Store, iBookstore, and Mac App Store account without a credit card
You'll need a plausible email address and physical address for the country you intend to use. Some people just pick the address of an Apple Store in that country.
You end up with an account without a credit card associated. YOu'll have to purchase and redeem iTunes gift cards to use it for anything except free content. I't my understanding this is possible online.
Once you have the new account you can use the Apple ID button at the bottom of most tabs in all the iStores to switch back and forth between accounts. You must be logged into the correct account to re-download content or get updates; so keep track of what you download from which store.