I would like to know if there is a check list or something like that to show me the steps that I will have to do to give my organization Web App Builder capabilities. I an not interested is using ArcGIS Online or Portal at this point but keeping everything simple and behind our filewall. A basic outline or roadmap would be ideal.
a place to start is Tips and Observations for getting Web AppBuilder - Developer Edition Installed
then once you are ready to customize, try Web AppBuilder Developer Edition – Customization Resource List
edit: I just noticed Robert already pointed you to the Tips.
Tagging on to the links that Robert and Rebecca provided, this link outlines the step to add custom widgets. If you move forward with Web AppBuilder you may want more widgets/tools than what is out of the box. Also, a great group to join is the Web AppBuilder Custom Widgets, posting discussions to this groups page will generally get the responses and answers you need for all things related to Web AppBuilder. Good luck in your research and decision making