Update and refine the online store in PHP, MySQL

There is a working online store with an admin, written in PHP
5,6.



What to do:
- update to the latest version of PHP,
- to improve a number of functions, for example, only works in the database
two currencies of the goods, you need to make the choice of the user, that he could create
currency and work on it,
- universalize the project for the possibility of staging on
any domain/hosting.



Also, several new projects are planned for the future, so
I am looking for a specialist in the expectation of long-term cooperation.