well, according to the information i heard, leve study is waste of time, beside you still have to take the test, i forgot the name,(i think it;s CAN-test) it;s similar to Toefl, i heard it;s harder then Tofle now.
You can not take regular courses unless you have registered full time or partime whcih they only offer in September and January. Depends on your program, you can take max of two courses as Special students, but it;s not garanteed that they can be transfered once you are Regular students.
I think you can register for esl classes, not sure about the procesedure, I know that they CAN"T be transferred as elective courses for your program.