1) Just look at Measles.
Nearly every American child contracted measles at some point before they turned 15 before a measles vaccine was introduced in 1963,
according to the Centers for Disease Control and Prevention. About half a million new cases were reported to the CDC every year between 1942, the first year it was tracked, and 1962.
Most cases went unreported, and the CDC estimates up to 4 million people actually caught the measles every year. About 400 to 500 people died, 48,000 were hospitalized and 1,000 suffered encephalitis, or brain swelling.
This went to 0 in 2000 due to the vaccine. Other vaccines have similar results.
2) I have no idea if this is true or if it matters. I'll leave it to the experts.
3) If it continues to show higher mortality it should and will be stopped. However they are modifying it to include live vaccine which, counter-intuitively, has been shown to be safer. Still, looking at the broad spectrum of vaccines they have been wildly successful in developing countries. Unfortunately they are not perfect, but on the whole they save millions of lives each year.