Iron Man has wielded the Infinity Gauntlet in the comics. But it's not a consistent occurrence throughout all comic iterations and often depends on the plot and creative direction of the particular comic run.
One common theme is power and responsibility. Just like in the main Marvel stories, when Iron Man has the Infinity Gauntlet, he has to decide how to use such incredible power. Another theme is redemption. Sometimes Iron Man uses the gauntlet to fix his past mistakes.
Sure. One great Iron Man Infinity Gauntlet fanfiction is 'The Gauntlet's New Master' which shows Iron Man's unique take on using the Infinity Gauntlet. He tries to use it for the betterment of Earth in a very different way compared to Thanos.
There are many speculations about the man in the iron mask. One theory is that he was an illegitimate son of Louis XIV. He was locked away with an iron mask to hide his identity so as not to cause a scandal or a threat to the king's power. Another view is that he was involved in some sort of political intrigue at the court. However, the exact truth remains uncertain and has been the subject of much debate among historians.
In the story, the man in the iron mask was a mysterious prisoner. His identity was kept secret, and he was forced to wear an iron mask all the time to conceal his face.
Iron Man's origin in the comics involves Tony Stark getting captured and using his engineering skills to create the first Iron Man suit to escape. After that, he continued to improve and develop the technology to become the hero we know.