Organic is better. The antibiotics will collect in the meat of the animal and affect the human who eats it. The antibiotics then throw off the balance in the gut and immune system of the human. Thus it would be better not to eat from an animal fed antibiotics.
Yes. It depends on what you are comparing it to.....Driving your car is riskier than eating meat from animals given antibiotics. However if you have the ability and the money to purchase meat from animals that were not given antibiotics and were fed appropriate food then I would say you should.