Does medium roast coffee have more caffeine then extra bold?

Yes, if by extra bold you mean dark roast. Caffeine is destroyed by heat, so the longer roasting reduces the caffeine content of dark roast coffee (contrary to popular opinion which thinks of dark roast coffee as "stronger" somehow). By the way, the darker roast also burns off many of the subtle flavors in good coffees, which is why a lot of mass-market coffee shops over -roast their coffee, to disguise the poor quality of the beans they are using. Ergo, dark roast coffee means less caffeine, less coffee flavor (but more of that delicious charcoal flavor) and thinner body.