Check these link:-
Converting InDesign documents for Kindle compatibility requires the following steps:
1. Export InDesign document to EPUB
2. Convert EPUB to Amazon-compatible MOBI format
3. Preview on Kindle device (optional)
4. Upload to Amazon store.
Regarding the two versions-horizontal and vertical views, please use indesign cs6, because in indesign cs6 , there is an alternate layout option is added that is basically for this purpose.
That’s ridiculous advice. Epub adapts automatically to the screen unless it’s fixed layout.
Bob , I believe Ashutosh said it in regard with the IPAD think..not for the EPUB...?
" And do I have to make two versions - horizontal and vertical so it can be flipped on an ipad?"
Well, epub does work on iBooks and doesn't require any special handling.
As for DPS it's a whole different topic and the OP should visit the DPS forum here: http://forums.adobe.com/community/dps
I will say this, there is no real reason to have both H and V layouts for magazines.