The half pack comparison is a little subjective, during the time I was smoking 4 PAD, half a pack didn't last long. The format seems good, can you rebuild the coils?
Nope. You have to use the vaporesso ceramic 1.4 Ohm coils. It's just about the stealthiest stealth vape I've seen and you give up options for that. It's something you can carry in your pocket anywhere. Well, other than through a metal detector, you'll have to put it in the little tray.