The PHB contains only one single optional rule in the Magic chapter: Components. This is Vocal, Somatic, and Material. By the book, a caster could be bound, gagged, and have nothing useful on him. If he has a spell memorized, he can cast it, no matter what(barring the combat fizzles).
In the DMG on the other hand, the optional rules consist mostly of how Wizards get their starting spells. The "core" rule for this is that the DM picks exactly what spells the player gets. In addition to this, it seems that the wizard also has to pay for his spellbook . . . by page. Now, it could be an interpretation problem on my part, but it doesn't actually say how much it costs to write a spell into a spellbook, just how much it takes to "prepare" a page.
Chapter 8: Experience
Following the core rules, a character gains experience for the following actions:
- Being actively involved in the game
- Making the game fun for others
- Surviving the session(without resorting to resurrection magics)
- When the player solves a difficult puzzles/talks his party out of hairy situation
- Achieving Story goals
- Defeating foes(notice this is not killing)
Next time: Combat!(finally)