To get famibne and catch skull do i have to com[plete campaign on normal?

Also does leveling up skill get you higher rank on xbox live?To get famibne and catch skull do i have to com[plete campaign on normal?
famine and all the other skulls except catch you can get without beating the game! but for catch you must complete campain on normalTo get famibne and catch skull do i have to com[plete campaign on normal?
leveling up gets you a diffreent symbol like Call of duty 4 but no new weapons to get famine and catch go to a walkthrough online or here is a link


the skull catch is on the fourth level and the famine is on the sixth level