Jarvis can be made more complex by giving him moral dilemmas. For example, if he has to choose between following Iron Man's orders that might be dangerous to others or disobeying to protect the greater good. This would show that he's not just a program but has a sense of right and wrong.
Usually, you need to complete certain side missions or reach specific progress in the main story. For instance, in some games, after you defeat a particular boss or complete a set of side quests related to a certain character or event, the DLC suits will be unlocked for use in the main story.
The number of Iron Man suits in comics varies. They keep evolving and new designs pop up frequently. But it's safe to say there are dozens, if not more.
One idea could be Jarvis getting a physical form and having to learn how to interact in the real world like a human. He could struggle with emotions and social cues, creating humorous and touching moments as Iron Man tries to guide him.
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.