The Bard is -- if we take the folklore about them, the PHB version, the Brave Halfling version, and whatever blog-baggage it has accrued -- a figure that is iconic but poorly understood. We all know what a Bard does, but we don't know how the Bard does it.
1) When they Charm, they seem to work magic like any spell-caster, but it's difficult to say precisely whether it's arcane, divine, or not even really magic. People are captivated by performers, and it's inexplicable. W.S. Burroughs agreed with Jimmy Page, after attending a Led Zeppelin concert that they were literally absorbing, manipulating and redirecting the power of the audience as in ritual [Zak pointed us to this superb 1975 article]. Is Jimmy Page a magic user or a shaman? What about Jim Morrison? He thought he was a shaman, and so does he stat up as a cleric or what? Or, are they both Bards (along with Robert Plant, Syd Barrett [but maybe not Roger Waters], Mick Jagger, and of course the dreaded Paul McCartney ... and Stevie Nicks, Madonna, Prince, Henry Rollins, Johnny Rotten, Lady Gaga, Jello Biafra, etc.). Maybe CHA modifiers apply, seems appropriate given the performance-dependence of the skill.
2) Reading Arcane Scrolls .... Bards do tricksy things, and so they are like present-day magicians/illusionists.