Once you click on the "save websites for later" button and it shows you a checkmark indicating it saved successfully, you just need to click the second button right below it and it will restore everything. I hoped it would be visible and clear since it's shown immediately on the front page.

I'm not quite sure what you mean by the little folder icon, but all the tabs should just show up directly on the front. Windows should say "Window 1", 2, and so on. In that way yeah it's a collection of tabs.

As for the shortcuts it's kind of a spaghetti of different operating systems having different shortcut conflicts, and so I've tried to make it so that it's easy to change the shortcuts to your own specifications. See: https://support.mozilla.org/en-US/kb/manage-extension-shortcuts-firefox (It's in the settings page for future reference)