Have you tried @Borders yet in their tourism section? I am sure you will find an abundance of different styled maps and tour guides for Dubai and the UAE there.

Where can I find Faber-Castell stuff?

Have you tried @Borders or @Art Materials ? I am sure you can find Faber Castell merchandise there.

Where can I buy I Love Dubai shirts?

I remember @Borders had a couple of shelves for these shirts and a couple of camel pics shirts.

Where can I find manga books?

@Borders has manga on offer

Where can I find a feather pen?

Sometimes @Borders have quirky things like feather pens near the cash register. Ask an associate, I am sure they will be able to direct you to find one if it's not in the store itself.

Where can I get Plastic Playing cards?

Try @Borders. I am sure they have really cool designs and cases for sets of cards as well.

Where can I find a library with good selection of English books?

@Borders and @Magrudy's both have an amazing collection of books.

Where can I find a good authentic Japanese cook book?

Check out @Borders , I know they sell a selection of cook books in their branches

Where can I find foam balls?

You could also check out @Borders, if you are looking for the foam balls aimed to use for arts and crafts