Katherine,
I use Pages for these tasks and have no issues with compatibility. I am not sure about the equations, since they don’t come up in my field (literature). But import of doc and docx, no problem. I send back doc files, with revisions/comments, and the Word user reads them easily. Picture handling in Pages is simple, since it’s a layout program. Pages has no trouble with importing my Scrivener RTF files, since they usually don’t have end or foot notes. And the doc export from Pages is no problem for Word users.
If Pages is not for you, try Nisus Writer Pro. With either program, you might exchange files with a Word-using friend to see how it goes.
PS: on the App Store, you may now buy Pages independent of iWork for $19.99. At that price, it’s worth a try. And if you do, check out iWork.com; where you and a collaborator may post files, review revisions, and settle differences via a Skype chat.