1. Actually my wife and son will not stay in a rental apartment but will stay in a hotel apartment in Canada for 4.8 months (march, jun, jul, aug) and (dec) by going 3 times a year. So they will have hotel bill in my wife's name.
With a hotel bill, I suppose it is good enough proof that they were staying in Canada. Very few people would pay for a hotel if they weren't staying there.
2. How can a PR holder not get medical from canadian government. PR card holders get free medical care in canada. So why are you saying to buy insurance?
Health care in Canada is provincial and each province has their own rules but all provinces have the rule that you are not eligible for their health care unless you live in the province for at least 183 days a year. Of course it is possible for someone to apply for health care, get it and continue using it without staying in Canada 183 days a year in the hopes that they will not get caught. However, if they are caught, the healthcare can make them pay back for all the expenses they have paid for them and this can be expensive because healthcare will make you pay back what they paid for you and not what you would have paid yourself and hospitals and doctors may have different price lists where they actually charge health care more than they charge paying customers. Therefore, it would be smart to have travel insurance to take care of costly emergencies but for routine visits because of minor things, they can pay cash.
3.In worst possible case, in your knowledge of past cases how many months do you think it has taken to renew a pr card where immigration has doubt and asks somebody to prove. Will it take more than 6 months?
Yes, it can take a couple of years sometimes and in the end, immigration may refuse to renew the card based on not believing that the person stayed 730 or more days.
4.We all stay in Abu Dhabi where my child attends an Indian school. My plan was to keep his PR active and send him for Class XI to canada as they dont ask for age criteria for class XI in canada.So he would not then lose a year.
Have you talked to a school in Canada to ask if he can be enrolled in a grade now that will cause him to not lose a year?
5.A few more questions for you: Can a minor with expired PR when he turns 18; return to canada with a travel document on the ground that he had no role to play in expiration of his PR card.
A person who doesn't meet the residency requirements but still hasn't officially lost their PR has a pretty good chance of getting a travel document to return to Canada if they argue that they were removed from Canada by their parents and are returning to Canada first chance after reaching the age of majority.
6. If i send my wife and child permanently to canada in the 5th year are they likely to be stopped by immigration if they enter via USA as they have US visas.Does a school create problem to give admission to a child with expired PR or a PR card holder who enters canada in the 5th year.
You mean if they have not stayed in Canada at all and try to enter permanently in their last year of PR card? It is possible that immigration reports them on entry for not meeting the requirements. It is also possible that they walk through without a problem. If they get reported, they can try to appeal for their PR but without having had a good reason for not being in Canada, your wife will probably lose her PR. Your son might be allowed to keep his because he is a minor. However, he can not stay in Canada by himself as a minor and if she loses her PR, she has to leave. If they are not reported, they can stay for 2 years straight and then apply to renew their PR cards as they will meet the requirements again. A person with an expired PR card is still a PR if they are in Canada so a school can not refuse them admission.