A little silent boy in a building in Castelia City is actually Zorua
Undella Town.
Yes you do, you will get to keep N's zorua after talking to Rood in the ex-team plasma's building(The one that follows N) in Driftveil city on the northeast part of town. You will get it at level 25 with it's OT(original trainer) set to N and it will thus be considered as a traded pokemon
undella town
You can get Zoroa in Castelia City.
You find items that can be sold to a collector in Lacunosa Town.
Yes maybe you can in places like black city and undella town after you complete the game. ^^ No. Black City has no wild Pokemon and it is not in White Forest. It is also not available in Undella town. You need to transport it from another generation.
thats not a town.
After you migrate the Event Celebi into White, you have to go to the north side of town (north of the fountain). In the second building on the left (maybe the first) there is a pair of girls on the left side of the bottom floor. Talk to them with Celebi as the first Pokemon in your party and one of them will reveal themself to be Zorua. The other girl will give you Zorua if you have an open party slot and a pokeball of some type.
Go to the Battle Subway in Nimbasa City. Walk around until you find the train for Andella Town
dive is given to you by a girl in front of a house in undella town
Beat the Pokemon league!
Sazanami Town is actually Undella Town.