The ePub platform is very limited and, as mentioned above, is not much better than PDF. You may be better working with Adobe's digital publishing platform (check out Wired UK mag on iPad to see what's possible quite easily). You can then publish to Apple, Android and Blackberry devices.
You will need InDesign CS5 or higher (CS6 offers the most features) as well as a digital publishing account with Adobe – and the ability to use it, of course. Both quite expensive but I might be able to help you out there if you are inferested, depending upon timescales, as I'm a designer / developer by trade (freelance) and have access to everything you need. PM me if you want to chat.