While you're not PR approved yet nor have eCoPR at the moment, you can travel and return to Canada normally using your TRV.
As for when your PR application is approved and if you're in Canada at the time of your approval, it is suggested you travel after you get your PR card in hand.. In case if there is an emergency after your PR is approved but you haven't got your PR card, in that case, you can apply for PRTD after you leave Canada.
As for U.S. route in returning to Canada, entering Canada without a PR card via U.S. by land is only if you have valid U.S. visa to enter U.S. in first place and not other wise. Here is what you need to know:
https://www.cic.gc.ca/english/helpcentre/answer.asp?qnum=064&top=10
If it is still not clear and if you're still confused, you should post the question in the travel relevant threads, there are many on this forum.