Will we be able to change the website code and settings?

If a client changes a website's code or settings that control how the website works, then there is no guarantee that the website will continue to work. If such changes result in my having to fix any problems, including code cleanup, then I will charge for the time required. Also, I would need to be apprised of exactly what changes had been made. This is just one reason why I strongly recommend against clients making code changes.