We just made a pillow in our sewing class last month. We added batting and a backing fabric to the pillow front. You can use muslin as it is not seen. The actual back of the pillow was another fabric. This also had piping along the edge.
You won't need to add binding on the edges as it would be hard to keep them lined up exact. I like to use 1/2 inch seams for pillows. Plus either zig-zag or use pinking shears to finish the edges. I used the serger which is another option.