I’m working on a project to build a chatbot for our website, which focuses on selling monitoring software. I need some guidance on the development side of things. Here’s what we’re aiming for:

The chatbot should be able to handle predefined questions and respond with pre-set answers.
It should also support AI-based responses for more complex or dynamic queries. We’re thinking of training it using a CSV file or data from a site URL.
We’re looking for a cost-effective solution that supports both predefined responses and AI capabilities.

My specific questions:

What frameworks or libraries would you recommend for developing such a chatbot? (e.g., Dialogflow, Rasa, etc.)
How can we integrate AI features (e.g., GPT-3/4 or other models) into a chatbot without significantly increasing costs?
Are there any best practices for training the bot with external data (like CSV files or site content)?
Any advice, experiences, or suggestions on how to approach this would be greatly appreciated!