Hi Ami ,
Have the variables issue anything to do with the import process? If not, please delete non-related posts from this thread and open new ones for distinct issues. Off-topic questions aren't allowed in this Forum (even if it was you who opened the thread).
Regarding the Supplier ID, ids are used as unique identifiers in most databases' tables, including the WordPress posts table. As Suppliers are a WordPress custom post type, they are identified by an id. All our default templates include the Ids too.