What is Heaven like according to Catholics?

What does a person experience who is saved, after their death? Are they going to have a bodily resurrection in the New Jerusalem, in the real world, or is it a spiritual existence? If in the real world, will their body have any relation to the body they had, including things like age, conditions like dwarfism or siamese twins etc? Will every day have a good temperature, the sun won't eventually engulf the earth, etc? What sources do we have on what actually happens for all eternity?