Regarding the question about why your registrar was still keeping a bound
accession book when you already have the information on assorted sheets of
paper that were legally binding and/or more comprehensive than the book:
1.  Just tradition - the base of the title registrar is, I believe, that
the registrar is the one who keeps the register.
2.  Convenient, easy access.  The book puts, in place, the major facts
about a string of accessions, whereas the legally binding documents
deal with the exhibits one at a time.
3.  This is a variation of 2 (above), but I had an assistant once who
had her own disaster plan.  In the event of a fire, fire drill, or
    anything that caused us to clear the building quickly, the accession
book was what she would take with her.

I don't think one should spend hours writing extensive descriptions by
hand, but a portable, short summary of what is in the museum could
(knock on wood) be very helpful someday.