I currently have two single-pole switches in one box, with the first/upper controlling an interior light and the second/lower controlling an exterior light. I want to replace the second/lower with a smart switch while keeping the first/upper as a single pole. The smart switch calls for a neutral wire and a ground wire in addition to the load and line. However, my box does not appear to have a ground, or the ground was somehow incorporated into a bypass.
If I understand correctly, the neutral wire goes to the three white wires that are bundled under a wire cap at the back of the box and pass from top to bottom without going through a device. The load wire is the red wire that comes from the bottom of the first/upper switch (and currently attaches to the bottom of the second/lower switch). The line wire goes from the top of the second/lower switch through the bottom of the box to the rest of the circuit. However, the wire running from the bottom of the first/upper switch to the bottom of the second/lower switch is bundled via wire cap with two other wires that come from the top and the bottom of the box. Is that supposed to be the ground?
Also, what is that other yellow wire that feeds into the top of the first/upper switch rather than being screwed onto the side?