At-Will Power progression hasn't really been discussed like Encounter/Daily/Utility powers have.

How many At-Will powers are available to a given class at Level 1, at what levels do new sets of At Will powers become available, and how many At-Will powers are generally available total, per class?

Wizards reportedly have Ray of Frost, Scorching Burst, Magic Missile, and 2 other Level 1 At-Wills. What are those other At-Will powers? I'm betting that 1 of them is Shocking Grasp, and the other is Acid based with ongoing damage.