Contract... I don't know the exact way that works, but I do receive a 1099 form for taxes instead of a W-2 --- something like working through the company but not for them? Perhaps one of the other instructors here knows the exact reasoning.
As the chief pilot put it, you work as often and as much as you want. There are no set hours, so you may freely determine your schedule. Having completed a brief standardization flight, I am now free to instruct at the school.
As far as contract duration, there was no set length. The numbers I gave you are based on average hours flown each month by some "full-time" instructors (meaning they see instructing as a full-time job and put in 5-6 full days each week) multiplied by the take-home pay. Hence you can fly less...and earn less...or fly more and potentially earn more.
Why does this make Epic a great place? Students and instructors are paired on an individual basis and scheduling is based on the student's needs. With plenty of instructors on hand, a student is apt to find a perfect match for training, not only in terms of schedule but also in terms of teaching style. Couple that with the new C-172SP's in the fleet (nearly all of the fleet...two even have G-1000's), it sure is a hard deal to beat.