MODx Evo. To screw up online payment (acquiring)

Now the order on the site is made in the form of a normal message sending through the form at the bottom of the page:
Texto oculto

The following functions should be implemented:

1. After filling in the form fields and clicking on the "Please Order" instead of the form without reloading the page, a block appears with the choice of the tariff Texto oculto. Castom radio buttons (design will be provided).

2. The user clicks on the option. Clicks "Go to Payment." After that, he opens the acquiring site, where he enters the card data and makes payment.

3. After clicking on “Go back to the store” on the online payment site, the searched page opens with a message instead of the “Payment was successfully made” form. We will be in touch with you soon.”

4. All the names of payment options, their cost and the date “until December 31” are edited on the convention page in the admin. The site is multilingual. Therefore, editing in 4 languages.

5. Also on the site there is a variety of the desired page of the convention - the seminar:
Texto oculto. It differs in a set of fields, but is functionally arranged in a similar way. The same functionality should be integrated there.

6. The ability to use the old (current) form should also be maintained. That is, the new functionality should be implemented in new MODx templates and the output will be templates:
- Seminar (without payment)
- Seminar (paid)
- Convention (without payment)
- Convention (paid)
So that when creating a new event, the administrator can choose which template to use.

7. It is important to note that the site is multilingual and has a choice of cities. For example, when returning from an acquiring site, it must be the same language and region as the original choice.

- Page template: Texto oculto
- Page in admin: Texto oculto

I'm ready to answer questions.

Price? Timeline?