Things I don't understand about cycling

[weakwarrior]

I was reading an article in espn.com and I have 2 questions:

"Whenever you see a team lined up at the front like that, you have to pay attention," he (Armstrong) added. "You know what the wind's doing, and you see that a turn's coming up, so it doesn't take a rocket scientist to know that you have to go to the front."

What's that mean? What exactly is the wind doing, what's that have to do with a corner, and how does going to the front help?

His performance also fanned questions about who deserves the role of Astana team leader.

Also, what exactly does the role of team leader entail? Isn't everyone just riding? Does it mean that your teammates try to ride in front of you to cut of winds coming from the front? How important are the advantages of being team leader?

I recognize that there are more than 2 question marks:).