Ehh....just call it Twilight Town...calling it TWTN makes it too similar to TWTNW...
Poster Duty, go to where all the shops are, like the moogle shop and the accessory shop, and with the trolley going around, and then go to the Notice Board
SB Street Rave: Go to where you go to do the Grandstander and Cargo Climb mini-games, and next to the Item Shop there will be a lady there, and when you talk to her she asks if you want to use the skateboard
Edit: Curse the fact that I type long posts that take awhile to type, inhiding got there before me @_@