1.) No clue.
2.) Usually. You save on shipping so that can be a good savings. Find out who is going to be there and make sure they have what you want. Take a cooler if it is not close to home.
3.) I like having things in my cages. The more you have the more you have to care for. I like things that are easy to care for and wash when needed. I do think snakes, especially young snakes, benefit from having cover and concealment but that does not have to be anything crazy. Often I will just use large clumps of moss.