Relevant rules are amply clear on IRCC website which can be referred on the link below:so the rule applies as per the below ,when you apply you have to be residing in Canada and residing in Canada means not physically present by actually residing .this clears the first part of my question .
There is no requirement that you (the sponsor) or your co-signer (if applicable) have been a permanent resident, Canadian citizen or Status Indian for the 3 years immediately preceding your application to sponsor in order to be eligible to sponsor your parents and grandparents; however, you must be a Canadian citizen, permanent resident or Status Indian living in Canada when you submit the application.
https://www.canada.ca/en/immigratio...sponsor-parents-grandparents/eligibility.html