The 'bumps' are normal and will form an angular line of stitches. It's really kind of a decorative effect and looks good.
There are many ways of decreasing some will create a taller, pointier hat, some will create a gathered top. It's all personal choice.
For 54 stitches you could also k7, k2tog around the hat. Knit one row even (no decreases), then k6, k2tog around, the knit one row even, etc. Do this till you have only a few stitches on each needle..maybe 3 or so then cut the yarn about 6 inches long and thread it through a yarn needle. Put the threaded needle through each of the stitches left removing needles, go through stitches again and tighten it up and weave in the ends.