Cataloguing: Making my own MARC record

This week's assignment is to learn the Tags, Indicators and Subfield codes of the MARC record and try to catalog a book independently and then check it against a MARC record developed either by the Library of Congress or from AMICUS our Canadian national catalogue.  During this assignment I registered with AMICUS so as to be access their free MARC records.  My library catalogue system automatically links with AMICUS and a number of other library catalogues in Canada when searching for MARC records for items that have not yet been added to our union catalogue.

My first attempt was for a newly purchased book by Sean Cassidy entitled Kazaak!.  There was a record in our union catalogue but is was incomplete and what was there was formatted in all capitals and looked questionable. This is what I was able to generate on a first try:

020 ## $a 9781554551170

100 1# $a Cassidy, Sean
            $d 1947
245 1# $a Kazaak
260 ## $a Markham, Ontario :
            $b Fitzhenry & Whiteside
            $c 2010
300 ## $a 30 p. :
            $b ill. ;
            $c 21 x 27 cm.

This was the very basic information.  This doesn't give anything in regards to subject or other notes.  When I looked up this record on AMICUS they had added one more tag as follows:

500 ## $a "A tell-me-more! story book"--Cover
This general note tag where variations in the title can be noted.  On the cover is a circular icon with a picture of a porcupine on it and the A Tell-Me-More! Storybook title on it.  It seems this book is one of number of books using a similar format.  It is not really a series though.

Now that I look inside the front cover of the book for a little more help in creating a summary note for tag 520.  I am curious to know what sources cataloguers use for such summary notes or are they all original creations.  Where does plagiarism start and end with these summaries? Can you just take the information of the back cover?

520 ## $a Spike is just learning about his new quills from his friend Rupert, but when Rupert gets into trouble with Bear, Spike must use his imagination and his won quills to save him.

For the subject tag I am not very clear on what subfield codes to be using and the whole part of using $2 if you are using a Sears subject listing. 

650 ## $a Porcupine

Here is my MARC record as complete as I can get for now:


020 ## $a 9781554551170
100 1# $a Cassidy, Sean
            $d 1947
245 1# $a Kazaak
260 ## $a Markham, Ontario :
            $b Fitzhenry & Whiteside
            $c 2010
300 ## $a 30 p. :
            $b ill. ;
            $c 21 x 27 cm.
500 ## $a "A tell-me-more! story book"--Cover
520 ## $a Spike is just learning about his new quills from his friend Rupert, but when Rupert gets into trouble with Bear, Spike must use his imagination and his won quills to save him.
650 10 $a Porupine