Here’s a link to a great guide for side-loading your ePubs into your Kindle Library. Note, you will need to download and use Calibre (free program). http://forum.xda-developers.com/showthread.php?t=2052638
To sort out the image for the Kindle Reader. I just renamed the JPG (cover) and MetaData files to the same name as the book, shut down Tablet, powered up, loaded Kindle App and the book and cover was there.
Take ePub file. Use Calibre (Free) to convert to Mobi. Copy Mobi file into Kindle folder on device (Nexus 7 tested). Load Kindle App. Book is there in library. Need to check how to get covers included.