Hi,
1. Not exactly. You can change your course to any field/duration.
2. In case you shift from (diploma to diploma) level, you do not need to notify/get change conditions of your study permit. If you change from (diploma to graduate) level, you need to apply for changes in your permit condition with IMM 1249, at CPC-Vegreville, Alberta. www.cic.gc.ca/english/information/applications/extend-student.asp