Edit button not displaying
This is actually documented in two locations within the CSS Menu Writer Documentation.
Check out the FAQ titled "Why does the Edit button not display in the Properties Inspector?"
Also, on the 'Creating a new CSS Menu Writer Menu' page within the Help Documentation
...there is the following note:
Note: If you working with HTML pages, Dreamweaver must have Scripts set to display under Invisible Elements. You will then select this script icon beside your menu to display the CSS Menu Writer Properties inspector.
* Edit > Preferences.
* Select Invisible Elements from the Category column.
* Make sure Scripts is checked.
* Click OK.