I think there are actually a fair number of things to do as a knight; as a knight you can still lead an army, you can still take part in intrigue, you can still be a diplomat/ambassador, you can still take part in religion, and you can still roleplay. You can still be elected to government office in realms that have such elections (which is partly why I think many people enjoy republics, just look at Barca's noble count).
Not so. As a newbie you don't have enough prestige for most of the things you mentioned. You can't change class, you can't be appointed lord, and you can't stand for election for govt office, until you reach a certain level of prestige, I think 10. And even if they hang in there long enough to get 10 prestige, it's still highly unlikely that they'd get appointed/elected to anything.
