What Kraco says makes the most sense. Either that or the people with a need of services goes there tells the center what he/she needs and then they use the delivery shinobi (remember that stupid arc from way back when) to deliver the missions to the various hidden villages. In any sense, that was just one of the plot holes.
My big questions is why is there a four-man team of reconnaissance/medic shinobi when Sakura is the only one who has had any sort of formal training? I understand that Hinata and Neji will deal with the reconnaissance part but what the hell is Shino doing there?
Furthermore, isn't it wrong to send a bunch of kids to fight THE ULTIMATE WEAPON?
btw Pakkun's voice really did sound weird. I hope the real voice actor protested until they get the series back to the manga storyline but i highly doubt it
I think Tenten is quilting sweaters for everyone back at home. Its the ONLY reason to be left out of the mission.