Inkscape's default scale of "0.039370" is throwing off measurements when I use the Add-Ruler feature. Is there a way to make the default setting always set to "1.0" when I open any new file?
Set all the options in the document properties to how you like it, then use 'File → Save Template...'. It doesn't matter what you put in the dialog for 'Name' or any of the other inputs, just make sure to check the 'Set as default template' box.
Note that this won't affect the templates in the 'Welcome' dialog, since they can't be changed. Inkscape will load the default template when you click the new-button in the toolbar, the 'New Document' button in the bottom-right of the 'Welcome' dialog, or when you open Inkscape with the welcome-screen disabled ('Show this every time' unchecked).