I believe the code you are looking for is B, A, B, A, Up, Down, B, A, Left, Right, B, A, Start; at least that was the code for unlocking all the levels in the NES Teenage Mutant Ninja Turtles game. I haven't played that game for almost 20 years; the code is permanently etched in my BRAIN!!!!!
Until nobles get to know you, they usually won't trust you with anything more than being a letter courier. But in the end all the noble missions are pretty boring. My suggestion with starting a game would be to do lots of travel, see the sights, learn what goods are good to trade and where you can find them cheap, kill bandits and hire companions you come across. Talk to the guild master, they are usually good for giving quests that can earn you some good money and experience although escorting caravans can get a bit boring so try to find a quest that takes you across the map. 6000 denars and ~4000 exp for escorting a caravan where you are going to go anyways isn't bad. And don't mind the "you have 15 days to get the caravan to its destination", from what I've noticed in the mod is that the time limit never runs out; for other missions it does though so be careful what you put off.