Firstly, the product ID isn't created until the record is saved. The logic being that the ID can be used again if you cancel before completing the record. When you edit the record, the ID will then be displayed.
Secondly, I don't think multiple options are an option with the book mod. Unlike dresses which come in a multitude of colours and sizes, a book only comes in one size, otherwise it's another book. For example, you would have a record for a soft cover version and a record for a hard cover version. That's the way I see it anyway.
Finally, I can't see the value in using Product Book for a Computer shop. It can be done of course, but you have to weigh the advantages with the disadvantages.
I think the standard version of Zen Card would probably do a better job. The various attributes give you so much more freedom where options are concerned. You can still group manufacturers, but you can do things like let your customer decide on how much ram they need etc.
Try not to confuse all the extra fields offered in Product book with the limited number in Zen Cart. If you set up a nice template using tables, you can add any amount of data in each listing. Even without tables, you can still create bulleted lists etc.
Have a look at the Zen Cart sample files for video cards as an example. Here's a site where you can run the demo and even choose a template or two while you're at it:
http://(sorry, site offline)/
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