I see this type of answer a lot to people's ID questions. Can't speak for all ID users but I'm trying to write a book and publish it in the shortest amount of time required.
I have decided to compose the book in ID for two reasons:
- ID looks a bit more inspiring to compose text in than a text editor
- ID is supposed to save me time tweaking the output for EPUB
I understand that the output isn't going to be perfect. BUT - I want it to be as perfect as ID is capable of before rolling up my sleeves.
I think this is pretty obvious but I see this response a lot...the knee-jerk response is "oh, ID user...must be a newbie that isn't ready for XHTML/CSS". That's not it, we just want to utilize what we got as well as we can first.
To respond to my OP, I don't think it is possible for ID CS5.5 to export the margin classes for wrapped images...at least I can't get it to do it automagically. Fix this in the generated CSS file, then save that CSS file somewhere else and use it as a CSS template for future EPUB exports.