You should not have been issued the eCOPR while outside of Canada, but it's unclear whether anyone would make an issue of this.
No, you don't need the PR card. You will need to apply for a social insurance number (given on the spot for new PRs at Service Canada locations) - that's what you need to work.
(You technically may be able to work without it if you've applied for a SIN and not received it but let's not go there.)
