[Koha] Custom Data on Spine and Biblio Search

Hello, I am from a small school district in rural Nevada. We are setting up our first Koha OPAC. In most of the schools, the teachers use a code from Accelerated Reader or Lexile to classify the book by grade level. Is there in way to update the MARC record with this Lexile number for example, that will show up on the spine label? Is there a way to show in the book search results the Lexile number? Is there a way to create a search filter based upon a Lexile number? Say I wanted to find all the book with a lexile range from 700 to 800? Thank you,   Joseph Lamb