Regional subdomains with limited functionality

On the site Tekst ukryty (Bitrix) it is necessary to implement regional subdomains with delimited access / functionality in the adminka and synchronization of the catalog of goods.

A few questions:
1. How is it more convenient (including for promotion - seo + context) to implement subdomains:
Ah. Tekst ukryty
B. Tekst ukryty

2. Is it possible to provide/implement functionality for subsequent independent addition of new regional representatives in the admin.panel of the site?

3. In what time frame is it possible to implement this project

4. Project Cost (Your Initial Estimate)

Mandatory requirements:
Functional for the regional representative:

1. Limited access to adm. Site panels (only permitted sections can be edited)
2. Ability to change the description and prices of goods
3. Ability to add news
4. Creation of own shares
5. Ability to replace logos, phones and page contacts
6. Ability to add your projects to the relevant section of the site
7. Email confirmation to customers (about the order, etc.)
8. Contact forms with duplication to the head office.

Please indicate your experience with Bitrix, experience in solving similar problems.
To conclude the contract you need an IP or LLC