As I never really got into the Warhammer universe as a culture or background (only played a few eldar games way back in the day) I hope what I managed to scavenge from Wikipedia was enough to make the post appropriate for the setting.
literally they do nothing, but depending on the value of the charm, if a time comes where something happens to someone in the group randomly... those with a charm are offered a bit of protection... sometimes.
Don't worry bout it! Just disregard the letter Carri sent you and skip the first assignment. That way you can post "This is what Jacks is doing on the black ship in the meantime" messages whenever you want.