[fourdoorsaloon]

1. are there any other challenge that I have not considered?

Always. NLP is a valid way to accept requests. Web crawling is a valid way to get data into the system. How do you tie these two together? How is the data stored? How do create relationships between the data in your system?

2. is the project feasible?

You have not yet defined your project beyond "like Siri or Cortana". What does that mean to you? How will you know when that has been accomplished? Can you first define a more limited scope for testing the feasibility of the different parts of your system?

3. will it succeed?

First you must define success.