Ok, as I work at blockbuster, I can give you the answers you seek.
Blockbuster buys all current and last generation games. Depending on the blockbuster you go to will decided whether they buy back GBadvanced games.
No. Regular corporate blockbusters do not buy or sell system hardware. That's controllers, memory cards, or console units.
Blockbuster owned GAMERUSH stores sell only games and hardware, but they are still localized in florida and some southern states. I lived in florida and I didn't see one, which leads me to believe that the few GameRush stores must be on the east coast.
And there you have it.