All babies and small children are given escorts (usually angels) to take them on the train and take care of them until a suitable set of adoptive parents can be found on the other side for the remainder of their thirteen months.
Do ghosts exist?
Yes. Ghosts are souls who miss the train. If you are violently murdered, commit suicide with regret, or are not properly laid to rest, you may arrive too late to get on the train. If you miss the train, you are stuck on the human plane as a soul until you can be laid to rest. You will then be given another ticket, and another chance to get on the train. Babies and small children almost never miss the train by themselves.
What can dead people do and not do?
The dead can do almost anything that the living can do, except die, reproduce, and age. They can eat, drink, and sleep, but they do not have to.
Do zombies exist?
We'll be going with the Harry Potter zombies here, for the sake of ease - basically, they're called inferi among wizards, and are dead bodies with no soul. If your character's body becomes an inferi/zombie, then they go into a comatose state until the body is laid to rest once again. Anyone may become an inferi/zombie.
Fandom Specific FAQs
Does my character still have his/her powers?