If I create a site in Muse, can I export the HTML and pass it along to a web developer to add additional hand-coding?
Muse is not intended to be a code generation hand-off tool for downstream editing. We recommend you do all of your site editing in Muse, rather than exporting the site from Muse and editing the code elsewhere. By staying within Muse, you can continue to use the full functionality of Muse to update your site. As soon as you move to altering the output of Muse, there's no going back (unless you're willing to re-make your changes each time you export from Muse). The HTML code output from Muse is not optimized for manual editing.
Choose Object > Insert HTML. In the window that appears, select the default placeholder text and Press Delete (Mac) or Backspace (Windows) to remove it. Choose Edit > Paste to paste the HTML code into the HTML Code field. Click OK to close the HTML Code window.
For detailed Instruction you can follow the article http://www.adobekb.com/building_your_first_website_pt04.html#inserting
Hope this helps