1) Well, they modify corn so that it's resistant to the herbicide glyphosate.
They also modify soy so that it has a high level of oleic acid, which is naturally found in olive oil.
Last but not least, they also have modified Alfalfa, where it consists of a gene that makes it resistant to the herbicide Roundup, allowing farmers to spray the chemical without damaging the alfalfa.
2) Honestly, some think it's good, being able to scientifically change food, then others think it's wrong, that it will end up doing more harm than good.
3) I think that it's good, that we can change food for the better.
4) It's great, that we have evolved in science that much to where we can change food.