Some of them are convexly curved intentionally. Wear hollows out the center (concavely). I haven't found any advantage between straight versus convexly curved drawknife blades. In either case I tend to draw them at an angle so that I'm slicing not just chiselling the wood.
Pegs, I have tried a arm load of draw knifes in varius shapes and sizes. I am sure that the wood you work and personal preference plays a part, but for me I like a straight blade with some meat to it. My favorite is a old Greenlee. Very similar to rwn2000's draw knife. Mostly use it bevel side down.