Add functionailties to custom admin panel

Expert in databases and PHP required for this job. I have a website [login to view URL] coded in core PHP with a custom admin panel. Current admin panel only records reservations (purchases) made through the website. It does not work as a backend to pull information into frontend. You can see how reservation record looks like in attached screenshot. Your job will be to add new functionalities to the admin panel to make it work as a true backend for the introduction of products (tours) in the website. There are two main types of products: day tours and travel packages. To see a typical product page, check: [login to view URL] Product pages like this are currently created manually at the frontend. Your first main goal is to enable adding new products from the backend, so that stats like product name, price, images, etc are pulled from the backend to the frontend. One of the images is the main image that shows in different sizes across website (product lists, product pages and shopping cart). When introducing the products, they should be placed in the correct product list category. Products will also be associated with suppliers at backend. You will then create a supplier admin in a sub-domain similar to current reservation record as shown in attached img, filtered with only the tours of each supplier. Anotther important feature of supplier admin will be managing availability for tours. This means selecting dates and date ranges from a calendar and defining a maximum capacity for each day. Website is multi-linguage and this has to be accounted for in backend. Finally, you will take care of URL re-writting to make URLs SEO friendly and without extensions.