Re: Superman's power level - Part 1
What-if Superman has super healing along with his skin invulnerability? Not to make him like Wolverine, but to give him limits as well. Plus, it would be another way of "hurting" him without kryptonite.
A good example of Superman with super healing would be from my fav Superman book: It's Superman! by Tom De Haven. There is a scene that takes place on Halloween night 1937, which is the first public debut of Clark as Superman (he was wearing the suit as his halloween costume, as in the story, the Superman costume is actually a left over costume from a cancelled sci-fi Clark's then-girlfriend from Hollywood was working on). Clark stops a henchman, working for both alderman and businessman Lex Luthor, from his car, that mirrors the cover to Action #1. Just as the guy is on the ground, and Supes is walking toward him, there is a robot inside the trunk (aka the Lexbot) that activates and throws Superman through a few blocks into the river (I believe it was the Hudson; this is New York, not Metropolis). Anyway, when Superman wakes up out of the river: he is bruised, exhausted, his ears are bleeding and ringing, and he's limping. He waits for around five minutes, which seems like a long time for him as the Lexbot is destroying sections of the city's street, before he's healed good enough to fight again.