Like a suitcase they run it through scanners and it can be subject to random check with them opening the box and searching through it.Does anyone know the protocol now for checking a taped up box as luggage? I have scoured TSA's website as well as the airline's site but I haven't found anything specific to boxed luggage.
No you can't. Not just any padlock.
Why not just ship the package via UPS or Fedex? I bet it would be the same price or cheaper in the end. Just double box it and bubble wrap/packing peanuts for any valuables inside the box.
Side note: I've got a couple of mailboxes at the UPS Store and I frequently see people bringing their actual luggage to ship via UPS instead of bringing them to the airport. Cost I would bet is the same. Then you just pack a small bag with a few changes of clothes, mail your luggage a few days in advance, and be done with it.
Sad to say this is what airline travel has become. Pack too many people into the cattle car (aka a plane) with no luxuries (or even working bathrooms in some cases) and charge obscene amounts of money.