Does Petro-Canada have any pre-paid plans that have minutes you can buy that never expire?

Unfortunately. there is no top-up option that will give you minutes that never expire. Here are pre-paid top-up denominations and their expiry dates

$15 - Up to 30 days of service
$25 - Up to 120 days of service
$50 - Up to 180 days to service
$100 - Up to 365 days of service

your $100 - up to 365 days of service how many minutes does this give you, and are the minutes broken down by month or over the year? Is this avail in nova scotia?

You get 440 local anytime minutes when you top-up with $100. Included minutes are good for 365 days. It is available in Nova Scotia.