Regarding B -- why can't the user just pick the category from a menu? Personally, I despise being asked to categorize my ask in English to an AI, as I have no way of knowing how much detail I need to provide to get my request into the right "bucket", or whether I've succeeded in doing so. With a menu I can do that in 3 seconds and one click, with immediate feedback.
Regarding C -- why does the date selection need to occur in WhatsApp? If a user has WhatsApp, they have a web browser. If a 3rd party has servers running WhatsApp bots, they can host a web server. Why not, from WhatsApp, link the user to a website to select a date?