Super key is the Win next to Right Shift. I may flip it with the Fn key on the bottom... not sure, but it's a few keystrokes in the firmware, so I'll see how it goes.
The double shift is because I got a little too cute when designing the layout. Every single button is completely reprogrammable, but ultimately I found that 30+ years of typing (poorly) on big American style left shifts has left me preferring a large landing spot.
Well, I didn't fully realize the depth of my addiction when I ordered the aluminum plates with the switch holes cut into them. :-)
On one of the three keyboards I made, I cut out the aluminum between those two holes which allowed me to set the switches in so the bigger and smaller one are flipped, which is exactly what many European keyboards do in that corner, but actually cutting out the room to include the full size shift would mean a more extensive rework to accommodate stabilizers. I'd originally thought I was being cute and copying what the Commodore 64 did.