Must your streams be live or do you have the option to upload video?

Must streams be screeen casts or can you stream off a webcam?

Can you charge for special videos like exclusive content? All I see is that subscribers can pay for private chats and emoticons and stuff like that, but I'm wondering about actual pay per view videos, such as if there's a particularly imporatant gaming tournament that you would like to charge streaming viewers. Are there other services that offer this that work with Twitch?

Can you do multiple streams at once? Such as a stream of your screen and another stream from a webcam of you playing?