Implementation of periodic improvements on Joomla

Search for a programmer with experience in the development of such modules, as well as the functionality presented on the site, namely a catalog of goods, designer of order forms, order calculator.
It is necessary to make periodic improvements of existing functionality, as well as the development of a new one.
Aimed at long and fruitful cooperation.
Experience with third-party APIs (Yandex.Cards, SDEC, etc.)
The site is built on the Joomla engine, almost all the functionality is self-written, from the catalog of goods to the shape designer.
In addition to the current improvements from the attached file, in the near future it will be necessary to develop a module for the exchange of data with 1C UNF. It is necessary to synchronize goods and orders with 1C. (description in development)
Installation of improvements to the site should be made in the form of patches, sources will provide.
Works are carried out under a contract, preferably the presence of PI or self-employed, it is possible to work through the BS (discussed).

at the moment, we are interested in implementing improvements from the attached file. (budget under discussion)

From you the calculation of the cost and timing.

address of the site with improvements beta.onstamp.ru