Hi,
They are important to do. Read the manual, it explains the purpose of the end exercises.
Regarding the neck: The neck is an important area. As we get older it is an area which can be injured more easily or just wear out, sooner than other joints or pivotal areas of movement. Similar to knees and back, only more delicate. It also relates to the C7 area on the top of the spine, which holds alot of day to day stress. If the movement hurts , or is uncomfortable, reduce the size of the circles. Focus on smooth, smaller circles. Even if they are quite small. Work in your comfort range. As long as you are making circles... With improvement, you can increase the size or extent of the movement as improvement is made. Perhaps work with sword fingers and putting healing energy into the C7 and throat chakra area. You can work from the front and just work on the backside through the front , or connect that area horizontally (throat and C7), and feel a nice horizontal energy connection, energizing both front and back points. Also focus on the tops of your shoulders. There are imnportant energy points there to. Think of really relaxing those points so you aren't holding tension in the shoulders.