How to properly organize the work of the VK chatbot?

Question

Machine learning

Good day!
Now I have several VK chatbots that pretend that they are real people. Reply to messages based on the number of messages already sent by this bot. I want to make the script smart - this means analyzing the phrase, searching for keywords and issuing a prepared answer (there are 5 of them in total). There are a large number of correspondence between bots and people. Now I want to take all this, divide messages into interrogative and non-interrogative ones, highlight the most frequently used words - these will be the "keywords", enter them into the database.
Am I right? What are the nuances in this case? What programming language and database would you recommend for implementation?