Answer 1

distribution to the end user is normally done in alpha and beta​ releases. when you release the alpha, it's usually to a select group who will give the code a workout. you fix any errors, then send it for beta testing,
then fix the bugs, and get it ready for the last distribution to the end user. if the code is for one user, they will perform acceptance testing then send feedback to you. if anything is outside of the specifications, then you have to fix it. if the user wants more bells and whistles, that's a new revenue stream...