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.
Spider-Man was not one of the characters who died in the Infinity Gauntlet comics. The story had its own set of casualties, but he wasn't among them. The plot was complex and full of surprises, but Spider-Man made it through.
In some fanfiction, Spider - Man might obtain the Infinity Gauntlet through a stroke of luck. Maybe it just falls into his hands during a battle in an alien - invaded New York. Another way could be that he is chosen by some powerful cosmic entity to be the wielder of the gauntlet for a specific purpose, like restoring balance to the universe.
He might use it to save his city from all kinds of threats. He could snap his fingers and make all the bad guys disappear, like the Green Goblin and Doctor Octopus. He's a hero, so he'd probably use it for good.