Swine Flu viruses can be directly transmitted from pigs to people, and from people to pigs. Human infection is most likely to occur when people are in close proximity to infected pigs. Human-to-human transmission of swine flu can also occur, thought to be in the same way as seasonal flu occurs in humans. This would be mainly through the coughs or sneezes of infected people. People may become infected by touching something with flu viruses on it, and then touching their mouth or nose.
You can not get swine flu from eating pork. Cooking destroys the influenza virus.
The exchange of proteins among flu viruses from humans, birds, and pigs is very common, and happens every year (and has nothing to do with genetic engineering). However, these combinations are usually only transmitted across the species barrier, so normally the number of people at risk is limited to those who work directly with pigs or poultry. Only occasionally do the combination strains mutate in a way that allows them to be transmitted from human to human.