There are a number of questions being asked here. Probably too many. As to the question about where you can learn more, there have been a hundred or so books published on chatbots in the past three years.
As to the question about whether it is worth having students build such a thing, the answer, of course, is yes. Students should build. It might be more than one lesson, however. They will learn from this as they should learn from building any new thing. If it excites them, all the better.
However, the leading question is about the advisability of using a chatbot as an educational tool. I'm going to give a lot of reasons why this is problematic, though none of them is probably definitive. I think a case could be made for the use provided that the thing can be built to answer all of the objections below.
The first issue to address is why do it. How would it be better than other available resources, such as wikipedia. While Wikipedia is not reliable on some topics (politics, celebrities,...) I've found it very useful in most technical subjects including math and CS. In fact, doing a bit of research on a question is much more valuable to a developing mind than just getting an answer.
The second, possibly more important question, is how reliable can you make it. Students need to get correct answers to their questions. A naively designed chatbot might be positively harmful if it gives poor advice. Even if it gives good advice, that advice might not be consistent with the course goals in which it is used. I think that it is an immense problem to test the reliability of any AI or AI-like program. I don't think that any AI can (or should) be used unless very significant resources are put in to validating it. That might not be possible at the scale of an individual course in CS, especially as such courses differ in time and by locale. Even the commercially available chatbots, backed by major corporations, sometimes give harmful advice.
The third concern I have is that, in fact, not all student questions should be answered. Or at least not answered immediately or completely. The purpose of education is not to get answers, but to encourage mental and personal growth. Sometimes an experienced teacher will send a questioning student back to the workstation to think more deeply about things before answering, knowing that the student can do it and will learn something in the attempt. More often than that, a good teacher will give a minimal answer - a hint - encouraging the student to fill out the explanation through some grunt work.
I think the last issue, above, is very serious. Education is a subtle business. It is the development, ideally, of a relationship between a student and an educator. That relationship needs to be nurtured and needs the knowledge of the student and her/his needs that only a supportive teacher can properly provide. Yes, I know that mass education today gives up some (even a lot) of that ideal, but until we can build R. Daneel Olivaw, we need to approach this with extreme caution. Note also that Socrates understood all of this about six thousand years ago and that the Socratic Method was developed partly in opposition to the idea of the Oracle at Delphi, which provided only answers.
