Please look into the following white paper which will give good broad technical overview of the combined Tableau Desktop and Tableau Server solution including architecture and process diagrams. let me know you have any issues in understanding this:
I suggest you to go through these articles all your questions will be answered.
Have a look at this video http://www.tableau.com/community/events/tableau-isnt-the-norm?signin=419c58b205ae7fe7cf3ca4d063a4181e
this will explains the insights gained and the experiences and education to navigate the complexities that organisations face, and how the simplicity of Tableau’s offering enables everyone to execute with ease, while having fun along the way!