You sure that was the plan since it didn't seem like everyone got on the bus or even attempted to get on the bus, just a small handful of people. If that was the plan then it must have been for everyone to get on the bus and just keep on driving until they felt like stopping because if they had a rendezvous point set up then it seems that Rick & Carl and Michonne didn't know about it.
Positive. Three different people said it, including the children. Somebody panicked and took off. Thus, the plan didn't survive first contact with the enemy. Although, I don't think they took into account the governor returning with a frickin' tank.