As for the Wizard and apprentice scenario. You really have to have two players really willing to roleplay that situation fairly. I'm always hesitant to put my players in a situation where one person is in charge of another, or the whole group. I usually find that a leader type character naturally evolves in the party, but you can't always predict who that leader will be. I've found that when I've assigned a leadership role to one person they either aren't interested in playing the leader or try to take advantage of the position.
I'm lucky to have gotten to know my friends/groupmates' role playing capabilities, so for me, it isn't too much to worry that they'll cry foul and hang me upside-down while they make off with my comics.
Speaking seriously, though, they would go for that, especially the two players that haven't read the books and don't know how magic works in the Dresden world. One player's brother will be rejoining us when he comes back for summer break from college, and would likely take the apprentice role if his brother's the full-fledged wizard.
But yeah, it definitely comes down knowing the group's habits and nature. I'm lucky to be in a group that's diverse and has the "combat wombat, one skill monkey, one social monster, one reality-defying freak, etc" like Samldanach's group, as well as a player that's a jack-of-all-trades and can pick up the slack when needed.
