The "DrumsUI_1680x1050_layout.xml" file belongs in your main EverQuest II directory (same folder as EQ2.exe).
To make use of this file, you would want to set your in-game resolution to 1680x1050 and then use this command:
/load_uisettings DrumsUI_1680x1050_layout.xml
As for your keybinds question, there is currently no way to set a custom keybind to a new window such as the Auto Attack bar. We as UI coders are stuck with making windows attempt to auto-show themself, and in the event that they don't, we fall back to the manual use of the
/show_window command.