Transferring international (JFK) to international (CGK) at CAN. Is there usually a delay?

Yes, there is usually a delay because of weather. And you don’t need to go through security again, but the liquid is not allowed if it’s over 100ml. As for wheelchair, you should apply for the service to the service counter of the airline in the airport, or tell about your case to your airlines in advance and they may arrange for you.