You need to prove that you are married to your husband = copy of your marriage certificate
.. that your husband is a Canadian citizen = copy of his passport
.. that you live with your husband in the US = documents showing official mail addressed to you and addressed to him at the same address + copies of both your visas for living in the US
Because a PR card renewal application should originate within Canada, you must mail it from inside Canada with a Canadian mailing address (friend or relative) but you don't have to be in Canada when it gets processed. When you are called to pick up your new PR card, you drive to Canada and enter with your expired card.
As for your other post, the IO was right to take your health card. You are not eligible for health care in Canada unless you live in your province more than 6 months a year. If you move back to Canada at some point, you can apply for a health card again.