You know, trying to find a flat version might be easier, but the seam may break up the look of the decreasing at the top of the hat that gives the beanie its smooth dome shape.
I am one to try anything with knitting as long as I tell myself that I am doing it for learning purposes. Sometimes the hardest thing to do is to cast onto the dpns, so starting with a circular needle is a pretty cool idea in this pattern because it will allow you to start the circle and then transfer it to the double pointed needles after it is already established. Because it is a baby item, it should go faster and if things don't turn out right, then you haven't wasted too much time on it. It might take you a few tries to get it right, but would be worth it. The need for a large number of stitches in the beginning is because you are doing a rapid decrease to make a ruffle edge of the hat like a brim. Make sure you know where the round starts and then after the first two rows are done, you can divide the number of stitches by 3 (or 4, depending on the number of needles you have) and transfer them to the needles. And then keep on knitting. Sometimes a tube or pointed baby hat is the best way to practice with dpns. Also, the web sometimes has limitations. I have found that when I get stuck, sometimes I go to my local yarn shop and show them what I am stuck on and they can help you there by showing you.