Hmmmmmm Hit and miss mate. Bit of heat and patience. Get them off fairly quick after trackday and possible call upon some solvent
Masking tape would be a better bet but yes as Shaun says, tape down first then group / briefing stickers on top of that. Masking tape is almost identical to 'application tape' which is used when applying vinyls, therefore peeling the two apart without leaving much residue will be much easier
If you do use masking tape to put the track day stickers on, use the low tack masking tape and not the normal masking tape
Yes they do, no problem at all. I don`t think they would put the sticker on to tape, the noise sticker is designed to tear when you remove it so you can`t put it on another bike.