Sales automation and customer management in agribusiness (microtechnics and fertilizers)

The client has agribusiness (sale of microagrotechnics, fertilizers). The main reason for looking for a system is the loss of customers due to the lack of a unified order accounting system and employee control. The main task is to automate the sales process of the site, which is hosted on Prom.ua. The process of system flexibility, simplicity and convenience for personnel is important. Also, the ability to change some functions on your own in the future. 1. Warehouse accounting. 2. Customizing the interface of program blocks for yourself 3. Sale of goods - machinery and fertilizers 4. Maintaining a customer base. 5. Integration with Prom.ua. 6. Import of base of contacts from a file. 7. Integration with Viber and telegram. How can these tasks be implemented in the system, do you need help from integrators?