Modifications of the site on Yii2

Hello, the task is as follows

Have:
Website in the great and mighty PHP (7.2), Yii2 framework

Have to:
1) Add replenishment of users personal account via API
2) Add a feedback form, messages sent through the form should come to Telegram
3) Add work through the API with the service (sending a file, receiving and displaying the result)
4) Set a limit of requests to certain pages within a given time from one IP (yii-RateLimiter)
5) General code review, update packages if required.

Requirements:
1) Dont break what works :)