The locations will still exist. But if you have to delete one later - you won't be able to replace it (past the number your current rank gives you)
often when i teleport to a loc, it send me through the floor and land on the floor below, so then i need to do that teleport again.
Hmm, I bet its due to the fact its not doing air checks like normal tp locations do, but that should only be an issue if you set loc where a block now is.
the tp location is on a glass floor, nothing have been built nearby. But it only happends when i teleport to an unloaded chunk. If i can see the teleport loc and teleport to it, i always land on top of the floor