Pagination is a huge topic and a bit too much to get into here on the Q&A. Here are my brief answers and I hope they help.
- Don't worry about duplicate content if your category/subcategory pages only show snippets for the products they contain and you don't have two identical category/subcategories. Similar category/subcategories will have a certain level of overlap and that is fine.
I recommend adding a bit of unique content to each one. Make it useful to the visitor. Help them find what they are looking for and teach them a bit about this particular category. This unique content will help you make each page unique and also hopefully help you rank for long-tail kws and convert better.
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Don't worry about implementing the canonical tag unless you see that you are having problems with multiple versions of the same page being indexed. URLs with Tracking codes for example.
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Make each paginated page have a unique page title (Category - Page 2 - Brand) and then implement rel=next/prev.
Read everything you can on this subject from Adam Audette. He has some very good posts and slides on e-comm pagination.
http://www.google.com/search?source=ig&rlz=&q=audette+pagination