Classic Theme Restorer add-on is the right for this purpose. https://addons.mozilla.org/en-US/firefox/addon/classicthemerestorer/

I want to change the location of the DIALOG that pops up after you use Ctrl+D or a right-click context menu to Add Bookmark. I am not asking how to move the buttons, I want to know if I can move the dialog independently in any way, or change the default position onscreen.

It is not possible to change the position where this drop-down list open as it is tied to the bookmarks star button.

You would have to move those two combined bookmarks buttons to a different position, possibly to another toolbar.

Was it always tied to those buttons? I remember having it pop up near the tab I was right-clicking. Is this something that just changed with 29.0? Is there nothing in about:config that can alter this? I do not even have the combo-star button on my bars, and the dialog is pinned to the left side of the location bar on the nav bar, which leads me to believe it can be set to appear in other places besides being pinned to the star.