no and yes.
i'll let someone else do the explaining on the second one.
no it doesn't read the GC save? or it does, but it doesn't benefit you?
were you answering both questions or just the bolded one?
sorry for being slightly confused.
No it doesn't read your GC saves
Yes it does connect to Wild World, but i'm not sure what kind of connection you're expecting. It's not like the GC game with the GBA adaptor, there is no island, but you can import your DS character into City Folk. However, i'm not sure if this means all of your status is transfered over (ie if you paid off your house, do you start off with a mansion??) or just the character him/herself and whatever is in their pockets.
You can also use the DS game to transfer your City Folk Character to another City Folk game in order to visit their town. When you speak to Rover or whatever his name is (the guy in charge of the town gate) he'll ask you how you want to visit another town, and this option is called the "DS Suitcase"