1. There are no mastery books before 4th job except for a few special classes. Paladins aren't one of them. 10 is the current mastery level.
2. There's not a lot of "must-do" quest lines but I guess for lower levels you can do stuff like Kerning Square and you can do Azwan to get your inner ability unlocked and later I guess Silent Crusade is good. Most of your EXP is probably going to come out of grinding on mobs though.