Sometimes my brain goes on odd tangents.
Pre-Crisis, was there ever a discussion about how being shot with a bullet felt to a Kryptonian? We all know that they could easily shrug off the projectiles, but did they actually feel them at all? Did one describe the sensation?
Superman could turn his hearing up or down. Perhaps he could also increase or decrease his awareness of physical sensations. If he was super-sensitive, he will have needed to be able to do this to avoid constant distractions.
In Action Comics #500 it was a plot point that his invulnerability made him insensitive to some tactile sensations. Luthor's agent scraped some cells from his hand using Kryptonian metal. The issue also has a bit where Superman refers to the sound bullets make when they bounce off flesh as one of the things he was first able to share when Krypto came to Earth.
I have a vague memory of a Supergirl story in which someone fires on her with a machine gun and she remarks that it tickles.
I would expect small arms fire might not be very noticeable to Kryptonians, but heavier firepower might.
Pretty sure Mary Marvel did that in a 40s story.
In Action Comics #484 which took place on Earth-Two, Clark Kent was made to forget that he was Superman by the Wizard on the behalf of Colonel Future. With this, he became more assertive and heroic as Clark and married Lois. On their honeymoon, as Clark was swimming in the ocean, an attack sub of Future's opens fire on him with machine guns (as Clark became a massive thorn in his side ironically). Lois saw this and was horrified then was amazed to see Clark not only unharmed but oblivious to the bullets. This led her to try the old "Let's-Cut-His-Hair" cliché which left her with a broken scissor and the realization that she was married to Superman! Everything worked out at the end!
Side-note #1: If Clark still possessed his powers, how long would it take for his new bride to realize that he never needs to shave? In fact, why didn't Clark notice that?
Side-note #2: Clark and Lois got married nice and legal but how did he take the blood test?
Side-note #3: The scissors breaking was an old bit from the Weisinger days. Just because they couldn't cut his hair, why would they break? Did Lois also have super-strength?
Obviously, the super-powered strands of Krytonian hair actually slice thru any Earth blade that comes in contact with them, destroying the scissors. Or not. Still, that answer would totally have fit in an old Superman letter column.
When exactly did it stop being a planet of Supermen? Suddenly Superman wasn't being affected at all by Krypton's gravity, just the its sun's red radiation.
Presumably, in the continuity where Krypton was a "Planet of Supermen", the bulk of the buildings and such would have been made out of some super-durable S/F material (Inertron-K, perhaps?) so that they wouldn't have to worry about crushing their own homes or pulling all their doors off their hinges. Said materials would most likely be x-ray vision proof for privacy as well.
It was established in some '70s or (pre-Crisis) '80s story that Superman always had to be in flight a little bit to prevent his weight from crushing sidewalks and such. I could buy that ...
But then there was one story when he couldn't fly for some reason so he kept himself slightly aloft by constantly exhaling from his nostrils at the floor. I mean, he's Superman, but he does have to inhale occasionally to continuously exhale, doesn't he?
I'm probably misremembering that story, but I do recall rolling my eyes.