I have reviewed your requirement as well all three tab in excel, which is defined the data type.
I explained you how system will work after completing my job.
you will login in control panel with secured username and password, you can able to change password time to time, just for security.
system will provide you all list of product uploaded in your stores with detail as you mentioned in the excel file, once you edit anything then that will reflect in your store as well as you can add or remove from the interface of the website. it will be simple and easy to use. You can also export your products detail in excel and you can add new product through excel.
I have few more idea, but i will share with you once you ping me in private chat.
I have 9 years of experience in PHP, Codeigniter, Yii and MySql
I have done the same job for ebay and amazone, but not show you, because i was worked for another company and signed for copyright.