Who made Darth Vader's suit? Who was it intended for? What was the
purpose of the suit (survival or improved performance in battle)? How
long did it take to make it? Was it ever tested by someone before
Vader wore it? Who performed the maintenance to the suit while Vader
had it? Were there ever any changes or improvements to it? Was there
ever more than one suit made? How did Darth Sidous obtain the suit?
Is this issue addressed in any books? Was this information put out by
George Lucas himself or an EU author?

Just as an example I know that at the end of episode 2 that Poggle the
Lesser had given the death star plans to Count Dooku/Darth Tyranus who
in turn gave them to Darth Sidous. The empire/republic built the death
star in about 20 years. It destroyed the planet alderaan but was than
destroyed by Luke Skywalker. A second Death Star was made but again
destroyed by the rebels at Endor.