The last first aid course I was on (which was specifically for osteopaths) had lots of role play discussions, interestingly when this one came up people were less concerned about the potential spinal injury for a cyclist (more about safety from traffic) than they were when it was a motorcyclist. Anyway, you’ve already got the right answers, if you can’t tell their breathing within ten to twenty seconds then you have to assume their not, also key is breathing normally not one gasp then nothing. google agonal breathing, a lifeguard was found incompetent for mistaking one breath for normal breathing and ceasing cpr. and current evidence shows little benefit from mouth to mouth, its the chest pumps which are most important, the blood is reasonably oxygenated for about six minutes of pumping.