There is no overflow pipe for the air con, it is a sealed system, there is a drain pipe however to let moisture out that collects when used, this collects under the evaporator, that is the bit in the heater unit, so will be under there position wise dropping onto the floor.
The fans are a concern coming on like that, they shouldn't they can however if it has logged a major fault in the ecu, so I'd get it checked for codes.
tabetha