New user...and I mean REALLY new. Never worked in C/C++ and never worked with the Arduino chips. Goal or general interest is robotics.
Since all the pins are floating unless otherwise addressed is it standard operating procedure to pull each on LOW or HIGH with a resistor or pull them HIGH with internal resistors or just ignore them? In other words are you overtly addressing unused pins?
I would only pull them up/down if you find they are interfering with neighboring pins (which can occasionally happen). I would suggest the internal resistors in that case :).