While you cannot resize the address bar, you can show as many icons as you want (until the search bar is totally too small). To do this, go on settings>customize and drag as many of the icons into your bar as you want.

Have a great day!!

-Jon

Note that if you place the mouse pointer between the location bar and the search bar then the mouse pointer will change to a resize pointer that allows to change the width of the location and search bar by moving the mouse left or right. The total size stays the same and only the relative size changes. You need to do that in normal mode (i.e. not in Customize mode).

Go to the Mozilla Add-ons Web Page {web link} (There’s a lot of good stuff here) and search for what you want.

I have an extra toolbar, and a vertical toolbar.