Explanation
To leverage a three column layout on a page and move the mini-cart widget from the right to the center column, the requirement can be fulfilled by creating a Gross Layout Override. This is a custom Visualforce page that overrides the default layout of a page and allows changing its structure and content. The user can create a Gross Layout Override that uses a three column layout and places the mini-cart widget in the center column. Salesforce References: B2B Commerce and D2C Commerce Developer Guide, Gross Layout Overrides

According to the B2B Commerce Developer Guide, the ICart interface provides access to the cart object and its related data. The Details property of the ICart interface returns an ICartDetails object, which contains information about the cart such as the currency, the subtotal, the shipping cost, the tax, and the grand total. The Fields property of the ICartDetails interface returns a map of field names and values for the cart object.
Therefore, to get the grand total amount for items in the cart and in the currency of the cart, a developer should use the expression {ICart.Details.Fields.grandTotal}, which returns the value of the grandTotal field from the cart object. References: B2B Commerce Developer Guide, ICart Interface, ICartDetails Interface

Explanation
The developer forgot to publish the storefront after making changes to the products. Publishing the storefront is a necessary step to make the changes visible to the store visitors. Publishing the storefront updates the site's metadata and content, and also triggers the site index and search index rebuilds. If the developer does not publish the storefront, the changes will not be reflected on the live site.
The following actions are not required or relevant for the scenario:
* Activate the product list. This action is only needed when creating a new product list or modifying an existing one. It does not affect the visibility of the products on the storefront.
* Rebuild the search index. This action is automatically performed when the developer publishes the storefront. It is not a separate step that the developer needs to take manually.
* Publish the catalog. This action is not applicable for Salesforce B2B Commerce for Visualforce, which does not use catalogs. Catalogs are only used by Salesforce B2B Commerce for Lightning Experience.
References:
* Finalize and Publish Your Storefront
* Customize the D2C Store Template
* Configure Public Pages for a Storefront

The service method that should be overridden in order to allow "without sharing" queries is ccrz.ccService.initSVCDAO. This method is responsible for initializing the service data access object (SVCDAO) that is used by the service class to perform queries. By overriding this method, the user can specify the sharing mode of the SVCDAO, which will determine whether the queries respect or ignore the sharing rules of the current user. For example, ccrz.ccService.initSVCDAO(ccrz.ccAPI.SZ_WITHOUTSHARING) will initialize the SVCDAO with the without sharing mode. Salesforce References: B2B Commerce and D2C Commerce Developer Guide, Service Classes, ccService Class