Do you have to have lived in Canada for a few years in order to join?
You have to be a Canadian citizen. To become a citizen, you must first qualify as a permanent resident. Generally speaking, you must be a permanent resident for three years* before applying for Canadian citizenship. So yes, you have to live in the country for a few years before you can join CAF. *three years is the minimum for most people. There is a bit of wiggle room for people who studied in Canada since they can claim a fraction of that time towards residence.