That depends on where you are in the story.
You start off in the Observatory, then you descend to the mortal world to start your job as Guardian of Angel Falls.
--- SPOILERS FOLLOW ---
You will return to the Observatory several times as part of the story. You might be able to return there via the Starflight Express (from the blue shining trees) if you have reached Alltrades Abbey.
If you've already beaten the story, then the Observatory is gone.
No, Dragon Quest IX is exclusively a DS title.
If you're at the point in the game where you've got full control over the Starflight Express, then the observatory has already ceased to exist.
You should buy Dragon Quest IX it's almost fully customizable and I don't think there is a level cap.
no you cannot
There are no items called 'dollar' in Dragon Quest IX.
I would get Dragon Quest but it's ur choice
NO!!
nothin
Alltrades Abbey
Corvus
The inn in Stornway.
They can be bought in Upover.