Question about bottom of pool - resurface or not?

Looking to purchase a home, however unsure what these round inground “cleaners” are, i cant find anything on google images on the web. Who knows when the pool was built, it still has a diving board. A few questions:

  1. What are the names of these and are they obsolete
  2. What do you think an average estimate will go for to fix this?
  3. Does the pool need to be resurfaced completely or can it be done it an afordable rate by patching the cracks?

Thank you Link to image: https://image.ibb.co/jsjznU/2018_09_22_180521.jpg