Firstly, I laughed at the title. xD
They all seem to just be things they decided to add into the game - I assume Game Freak meant no real connection. They just do it to freak you out. :P
The ghost girl is creepy nostalgia from previous generations - in the Old Chateau in Eterna Forest, and on the Skyarrow Bridge + Scary House in Gen V there are ghost people that have no animation in their legs when moving across the tiles. So maybe the Ghost Girl has no part in this connection, however apart from that this wonderful link shows a nice theory that can prove they are connected.
The hex woman in the hotel put up the notice in the station, with the "usual place" being the hotel. She wants to hear the elevator to make sure this mysterious visitor comes. The ghost girl could also be part of this connection in a few ways:
- This ghost girl may know who wrote the poster, and she wants to find the woman who wrote it to... 'do stuff' to her, whatever that may be. o_o
- She may be the mysterious visitor, and she doesn't know what the usual place is, and she's looking. :P
- The ghost girl and the hex woman may be the same person and since the poster has been up there forever and the visitor hasn't arrived, therefore, she's looking for the person.
So yeah. My opinion. :3
Of course, we don't know who about this until Game Freak speaks up. Otherwise, theories will remain unconfirmed theories. Though I personally believe the theory in the link is a great theory, and is probably it. :D
Also, there is a 99% chance that the guy won't disadvantage your gaming experience if you don't tip him. If he does, the internet hasn't found out how he curses you yet. :P
Hope I helped. :)
Source: Above Link and Experience