Rewrite a Store Management Website

Hey, I have a store management website that i want to rewrite. Overview: the website manages the clients and the sells done in the store. I want to improve the functionality and add the following features: 1. SMS campaigns to users 2. Manage workers 3. Manage Inventory and codes Features of the system: 1. login required (there is one manager and other workers) 2. [Manager Mode] Create\Edit and Remove Workers Each Worker has a username and password so he can login 3. [Manager Mode] Create\Edit and Remove Products Each product have a: a. Code b. Name c. Cost d. Price e. Sell Price 4. [Manager Mode] View Cash Flow for specific time period a. selection of period b. can select by worker c. should view both summary and transactions and work hours 5. [Manager Mode] Start\End Worker shift NOTICE: this is only if the manager exists, otherwise the login\logout of the worker to the system should do the work 6. Register A Sell - Main Mode a. should ask for the client (search for Id, name or phone) b. once the client selected it will move to order show and on the side it will show the client details like: Id, name, phone, location, member since, points, total purchase, last purchase value and date, link to view history c. worker can add items and edit final price and discount and points d. Click next and the worker will insert his name and how many points the client want to use if he has e. click Done 7. View Client History show transactions with ability to return product (should calculate user history and gift points) 8. SMS Send a. need to do a simple page that can broadcast an SMS to specific clients based on Age, Interests b. every day SMS will send to those have a birthday c. every day SMS will sent to clients who didn't visit back for a long time d. SMS will be sent to a new client Work contains Basic HTML, MySQL and PHP Notice it's a rewrite so some functionality already exists