Open the vorpX menu (Delete key) and arrow over 4 pages to Input Settings. There you will see settings like this:
vorpX Gamepad Buttons = Thumbstick < >
vorpX Gamepad Button 1 = Menu < >
vorpX Gamepad Button 2 = EdgePeek < >
You can change Thumbtick to be Start/Select buttons instead, or you can change both buttons 1 and 2 to be Off.
For changing the size and width of the HUD, there are some scale sliders on page 2 Image Settings:
Game HUD Scale = 1.00 < >
Game HUD Scale Horizontal = 1.00 < >
Game HUD Depth = 0.90 < >