If everyone on the plane jumped at the same time the plane would dip slightly and then return to normal flight. When everyone is mid-jump their weight will be momentarily removed from the plane. So the plane would actually be carrying less weight for that fraction of a second and its lift would continue to be the same.
These temperatures are approximately 45 degrees or higher in the baggage hold and 65 degrees in the bulk area in Fahrenheit. While the temperature of the cargo areas will vary by the type of plane based on size and other engineering factors, all planes will have a controlled temperature similar to the Boeing 767.