The 'Save As PDF' menu command is only available with Firefox 56 or later versions.

The 'Preview' button on the Print Edit WE toolbar will switch to the Firefox print preview window, if you are using Firefox 56 or later version. Otherwise it will open the Firefox Print dialog.

When you click on the toolbar button to suspend editing, the Print Edit WE toolbar should be removed - that is the whole point of suspending editing!

Print Preview can be accessed by right-clicking on the toolbar button, or by using File > Print Preview on the Firefox main menu bar, or by putting the Firefox Print button on the toolbar.