actually, the superman blue/red origin *and* correction was *never* adequately explained. Something they did on purpose, I believe. I have ever single issue from that period, and I can guarantee you it wasn't.
as for the power changes, I think it's safe to say almost all of that was retconned out again. He can travel nearly as fast as the flash in most of their team ups (flash can exceed the speed of light). The birthing matrix I know has been retconned -- recent retellings show him a baby when leaving Krypton. I think it's safe to say the stupid force field crap has been recognized for what it was (stupid) and quietly ignored out of continuity (try finding a source in the last 20 years that mentions it).
The "S" origin changes every other week. Sometimes it's still Kryptonian. Sometimes his dad. Sometimes his mom. In "The Kents" its origin was a Delaware Indian glyph for healing (entered the family from a half-Delaware ancestor who married in during the last half of the 19th century).
It's not the only thing that has that issue. "Officially" Superman and Lois can't have children because they're different species. However, in the DC 1,000,000 storyline there is a character who is a descendant of Clark and Lois.
I like how people think things are ever "official" when it comes to comics -- which of the 6 "official" origins of Supergirl is accurate? Go ahead back and read my column on ret-conning.