I think you would need something more like Christopher Columbus's exploration to the new world (America). Columbus took three ships and 88 men and was at sea for five weeks before discovering land where food, air, and water were abundant. If he or his crew needed a breath of fresh air along the way, all they needed to do was walk up on deck. In addition to the provisions they carried on board, nature provided them with food from the sea and fresh water from the rain.
By contrast, astronauts traveling to Mars will need to be in space for approximately 2 years round trip. They will have to breath bottled air every second of the journey. There will be nowhere to turn for help if their supply of air, food, or water is compromised. Accordingly, like Columbus, they will need a flotilla of support. Four astronauts packed into a tin can (like the Apollo astronauts) just won't work for a round trip to Mars - the journey is too long. If something goes wrong as in the case of Apollo 13, they won't be able to get back to earth in just a few days. They will need to be equipped to handle every conceivable emergency - including medical emergencies.
Four astronauts in space for two years is equivalent to 8 man years in space. Someone is going to get sick or injured. You will not only need a doctor, but a complete medical staff and all the necessary equipment to deal with disease and traumatic injuries.
What if there is a tank explosion (like Apollo 13) and shrapnel crashes through the skull of one of the astronauts?
What if they have a hard landing on the surface and one of the astronauts suffers a punctured lung?
It would be erroneous to think that under-equipped laymen could be trained to respond adequately to the myriad of emergencies that might occur - and referring to a "CD" with instructions won't help them anymore than any of us have been helped whenever we have tried to diagnose our ailments using the internet. And if you think that calling physicians on Earth for emergency medical advice will help, don't forget that it may take up to half an hour for a radio signal to get from Mars to Earth and then back again (not to mention the time it would take for physicians on earth to formulate a procedure). Also, there would need to be many back-and-forth conversations between the astronauts and the physicians.
No. Four guys in a tin can is totally the wrong scale. You will need a flotilla with hundreds of support personnel and lots of infrastructure before the first manned landing vehicle descends toward the surface of Mars.