Sections and categories in Joomla are used primarily for navigation purposes (and in Joomla 1.6 to come, access). Generally a section and/or a category are assigned to menu items. If we are going to add menu items, then it's probably (but not necessarily) appropriate to add a category for it.

In the case of the Customer Service items, you should probably have multiple articles listed on one page. For example: "Shipping/Returns, Preview Policy, etc" on one page so that your readers aren't clicking all over the place to get their answers. In which case, they could all be assigned a category of "Customer Service" under the section of "Store" or the main section could be Customer Service, as Store is not really used as a section since it's categories are part of the Zoo application.
So, unless you are going to have sub-menus of each of those topics and one page each for those articles, keep them on one category.

Just depends on how you want to do it.

Also, you don't even really need separate categories for those articles if you want them all on one page. You can still just have a "Customer Service" category and have the menu assignment refer to just the individual article if there will ever only be one article on the page for that menu item.

Bottomline, use sections and categories as sparingly as possible. You'll end up duplicating the key words in the url because the url will include the category name and the article name.

So, if you find that you are putting what amounts to an article title as a category title, you are probably being too detailed.