as for the permissions side you are golden there. Linux is pretty much a "idiots nightmare" quoted from my UNIX/Linux professor. what he means by that is people just want to go around doing all this stuff to their computers without using their brains. well linux doesn't allow. it is best practice to keep urself as a normal user and not be root. yes u have to be in root for certaint things but not all the time. good luck sir!
and no i dont think an anti virus will be needed either. we had a lab in our class and it was to go and search for a virus. out of the 24 computers none got infected... (we downloaded everything under the sun)