20. If an ETA is issued with a work permit/study permit, is it valid for the length of time of the work permit/study permit or is it valid for 5 years (or when the passport expires, if it's before 5 years)?

The validity of an eTA issued to a visa-exempt foreign national alongside a work or study permit is independent from that of the permit; therefore, the eTA is valid for five years or passport expiry, whichever occurs sooner. That same eTA can be used for multiple entries to Canada, including after March 15, 2016. In addition, the eTA is electronically linked to the individual's passport; therefore, s/he must use that same passport when travelling to Canada.