When building out your categories make sure you are familiar with how they will display on your storefront. PSS does not have control over the design of your website so you will need to take of the display in the Magento admin area and possibly in the HTML/CSS of your site. You will be responsible for linking out any promotional banners, tiles or other design elements.
In order to allow PSS to monitor/maintain your cart and products, PSS recommends that you do not add any products external the PSS catalog while the installation is still new. Ideally you should have a cart installation that only carries the PSS catalog. After you have 100,000 PSS products up on your site fully functional for a period of 90 days PSS would then authorize you to add products external PSS.