Consequences of dynamically changing input/output configurations of digital pin?
There's no problem reconfiguring pins.  It happens all the time.  One example is with ping sensors where the pin is used as an  output to send the ping and then switched to an input to wait for the response.  The only caveat is that you must be sure what you're connected to.  For instance, if you set a pin to OUTPUT and LOW and it just happens to be connected to a HIGH OUTPUT then you just fried your board.