Will all the different NPCs all come to your one house as I've been building small houses for each one?
NPC's don't need "houses" but "rooms". You can just make a single house with enough rooms for each NPC. I would suggest you to follow some tutorials for the room formatting, or maybe the infos on the wiki could be enough.
Ah I see thanks! Ive built each one a small house where I first meet them on my travels. I will knock them down and wait for them to come to my main one
Oh? I'll check that out. Can the terrian sometimes cause the NPCs problems? I'm worried that where they are now is quite hard to travel from. Its saying the house is already occupied(???)
NPCs will teleport to housing, surrounding terrain (or lack of it) isn't an issue, unless it's corruption. NPC's won't live near corruption (anywhere onscreen). Post a screenshot of your housing and we'll try to see what's wrong.
If it's occupied then it probably means it's occupied by another NPC. Those little flags with the NPC heads indicate that the NPC is living there. And NPCs teleport to their homes, you'll never see the Dryad taking out her walking stick and going on a journey.
I guess the problem is that the worldgen tiles (or precisely, the tiles that have been generated and not placed by players) are not counted up for the housing. Also I would suggest to make simple rooms, like this Just make sure there is a decent light, a flat surface, a confort furniture and the entrances are sealed by Wooden Platforms or Doors.
Because that is considered only one huge room. Each room should be divided by the other with tiles, wooden platforms and doors and follow the internal minimum requirements of a flat surface (like a table), a confort furniture (like a chair) and a decent light all around the room.
It isn't sectioned off into individual rooms. Look at my house. Notice each room has a light source, table, chair and door.
You want it to be like a hotel, with each NPC having their own table, chair, light, door, within the larger structure.