1) The faster you go the smaller the angle of attack, hence the same lift at a higher speed. The smaller the angle of attack (at a given speed) the smaller the lift. So taking speed, wieght and AoA as an equation, it's always constant for level flight. I tried to simplify the explanation, so I hope it still makes sense.

2) For the most part you get drag whenever you generate lift. There are other sources of drag, however.

I'll let the others answer the rest.

-Q.