Is volunteer work considered customer service?

No, customer service and volunteer work are totally different. volunteer work is something you do for free, customer service is when you are working say at a clothing store and some one needs help finding something or need help on what clothes to pic, thats customer service.

The advantage of administering personality tests on employees is that it will allow the employer to know the mindset and personality of the employee. this will allow the employer to at least have an idea as to how the employee works and how his attitude in the workplace. the disadvantage is that it may make the employee a little anxious as to whether he would meet the personality requirements of the employer and whether he would be able to retain the job or not.