There's been a general consensus that, had Stane not "suddenly developed Stormtrooper aiming", it would have been a very short climax. Here's the kicker, though: anyone who's ever fired a gun can tell you that, even with a good sight, lining up a shot takes practice. Stane was aiming a very imprecise minigun mounted on the outside of a mechanical arm the size of a tree trunk indirectly; odds are he would have emptied his mag before he nailed Tony even once. Tony preempting him by disabling the targeting module was the smartest tactical decision made for the entire battle.
Dummy is the first robot/AI Tony Stark built. He's built others over the Marvel Cinematic Universe: Jarvis, Ultron, Friday, Karen. But Dummy is still his favourite, not just for sentimental value (no matter how much he may deny it) but for it actually having hardware that can enable him to help out as a lab assistant in his designing gadgets.
Fury's comment that Stark isn't the only superhero in the world makes sense considering he worked with Captain Marvel 13 years earlier.
The scene where Tony flies too high and the suit shuts down from the Icing Problem has quite a few parallels to the myth of Icarus's fall, where his reckless pride wrecked his flight flying too high to a celestial body where the difference in tempterature caused the fall. The key difference is that while the latter's wings of wax melted from flying to close to the sun, Tony's armour froze up in ice when he flew too close to the moon.
During Iron Man's first battle in his Mark III suit. Unlike most of the fights from then on, he does it with no quips or one-liners. On the surface it would seem, the reason for that was because he was pissed off at the Ten Rings for what they did to him and his company, but there are more layers to that. The fight takes place in Gulmira where his fallen friend Yinsen used to live, so that's one part of it. Since the Mark III is essentially the Mark II suit with a different metallic structure and updated weaponry, it has the same camera zoom features the Mark II was equipped with, as seen when he used it to spy on two kids on a Ferris wheel during the test run. Iron Man, while flying over to Gulmira, was already watching what the Ten Rings thugs were doing to that man and his son before he landed there. Tony himself knew what it was like to lose a father and didn't want that to happen to the kid. He wasn't just simply mad, he was showing Tranquil Fury.
Tony really didn't had a choice but to dismantle the weapons division even if he didn't felt guilt ridden by the deaths of the soldiers. The US government was looking into Tony's disappearance and feared he may have been working with the terrorists willingly for a quick buck. Had he not dismantled it, he would had been arrested and likely killed by Hydra who makes it clear he can either join them or die and given how he already refused to help Ten Rings, it is unlikely he would even consider their offer.
Yinsen describes the shrapnel in Tony's chest as "barbed", apparently deliberately designed to work its way further into tissues with every movement and deliberately difficult to remove surgically. (There are plant awns with a similar design.) He said that he'd seen this fate befall many in his village, men who would die within about a week after getting hit in the chest with the stuff. Imagine knowing that you were going to die, feeling the barbed shrapnel working its way deeper with every movement, every breath. And that was by design. With terrorists using them, you can bet it wasn't just enemy soldiers getting hit with the barbed shrapnel, either, but farmers and peaceful villagers and children....