Sarah,
Trigger shoes are legal. As are replacement triggers.
Stick-ons on the comb are 'probably' OK. AFAIK, GC is saying that a thin, single thickness of material doesn't constitute a significant change and is acceptable. I 'think' that a large, thick, stick-on/lace-on/glue-on cheekpad will still come under the prohibited 'attachment' rule. Hopefully, this will change with the next committee meeting.
If it were my local match, I'd tell the competitor that it was fine by me but that if he/she went to nats with it there might be complaints. (I have seen pads around 3/8"+ accepted at nats -- but the people using them weren't winning anything and attracting attention. IMO you can get away with almost anything until you win...)
Enjoyed meeting you folks at Winnsboro.