The LEDs are pre-bent, so mount the LEDs on the component side.
There should be a photo in the Assembly PDF guide on how it should look.
If mounted horizontally, you want your LED colors to be
.. and of course, the jumper soldered on the HORZ holes.
2)I want to orient the VUs vertically. What do the Vertical/Horizontal headers do exactly? Isn't flipping the board enough?
If mounted vertically, yeah, I guess you can flip the VU meter board upside down. (Yeah, that's easier. )
or you can solder the jumper on the VERT holes and mount the LED colors as
The original reason why I have the HORZ and VERT jumpers was because I originally planned the VU meter to mate with my Mini-IO PCB. I can't flip the board upside down because it will interfere with the switches and jacks.