The pads up top are for a Common Cathode Two Color LED. Pad on the left is the "Active/Bypass" color, pad on the right is the gated color.
The pair of pads are for the Key input jack. You'll need a 1/4" switching TRS jack for that. Left pad goes to the Tip lug, right pad goes to the Switched Tip lug.
The group of three pads nearest the bottom are for a mini SPDT slide switch. (Threshold Range switch)