I was wondering, what happens after we all land in Frankfurt? Do we disperse to our host families from there, or do we go somewhere else...? And what sort of things do we do together during our stay in Germany?
You should go to your host families . If your host families are not providing you stay then you should go at hotel in a unity then your fare is less.
It all depends on the organization. With YFU we are being picked up in the airport by our language camp supervisors who accompanied us to our designated language camps. From that train station our temporary host families pick us up.
With AFS, we got either picked up directly from the airport by our hostfamilies, or had to wait and take a train to a station, where our hostfams and regional volunteer coordinators met us. So we were with our hostfamilies by the end of the first day. Also, you really don't see anything of the other exchange organizations until the meting in Berlin near the end.