To read epubs on your Mac you can use the Adobe Digital Editions Reader:
http://www.adobe.com/products/digitaleditions/
Not sure if it affords more control though --- what sort of control do you wish for?
To manage (non-DRM) files you can use Calibre:
http://calibre-ebook.com/
It's been a while since I used it --- it probably has an epub viewer in it as well.
William