I am guessing if I use this plugin, I need to disable the default icon from the Backpacks plugin? Or does that icon get disabled if this plugin is loaded?

This question is answered in the FAQ in the docs. You have to disable the button in Backpacks.

I've updated the Backpacks plugin to automatically disable its built-in GUI button (hides the button if currently shown, and updates the config for you) when it detects the Backpack Button plugin.

doesnt seem to be working for me just keeps the normal GUI from the backpacks plugin 

Tinja

doesnt seem to be working for me just keeps the normal GUI from the backpacks plugin