The first thing is to break your project into more easy to chew pieces. Perhaps the first goal will be to get your motor moving from one extent to the other, controlled by a switch.
You may find using a stepper you won't need to have limit switches also, but it's not a bad thing to consider. The Arduino has several libraries for controlling stepper motors - like this one
. This example
talks through the method of controlling two types of steppers using a potentiometer. That could simply be adapted for a switch in your instance.
I don't think either of those methods will be good for your 120ft goal, as RFID requires close proximity and iR is light so subject to inversed squared law for distance and also prone to daylight interference so that's something else you'll want to develop - whether it's done via some other wireless means, or wired, as you work your way up to this.
For an iR controller, there's some great tutorials and explanations over at Adafruit's learning system
that I found very informative and contains everything you need not just to do the job, but also understand the theory. I think you'll find they also have some good stuff on RFID too.
Stepper motors are DC so while you state it will be powered by AC I presume you mean you'll use some kind of power supply from a mains source - with a DC supply for your motor and driver circuit.
Hope there's something in there that's useful - all the best with your project !