During the review process you can use Microsoft Word's review features, or you can just print out the document and have people review it by writing on the copies. Studies have shown that reading from a computer screen can reduce comprehension, and the chances of picking up errors in the content. The printed form also enables almost anyone to review the content. Having said that, we recommend you publish to the other output formats so you can see how your structure and format work in each output.
There will probably be several rounds of changes during the authoring process, for both the text and the graphics. You may need different formats of your graphics for each output. If you are handling graphic format conversion yourself, you'll only want to do it once, after things are finalized.