Hello,
First, I saw it for the second time last night and, although us comic fans are on the fence about the kid and the movie, clearly the females in the crowd and the majority of "average movie go-ers" LOVED this movie. Last night, just in my line of sight, I saw 10 girls crying. Watching Superman getting beaten was hard to watch...watching him fall was hard and, most of them, cried when the kid kissed him. Personally, I loved the movie except for the fact that it was too close to the original.
Anyway, I usually ask my fiance (a non-comic fan) what she thinks about the movie and she agreed that LOIS and RICHARD both know it is SUPERMAN's kid from the beginning. When she said "how could you leave US like that", she was not referring to the world, she was referring to her and the kid. She obviously was shocked when she saw the kid throw the piano but that was because she was unsure about him getting powers...they made reference to him being "fragile" and bad in gym. As for RICHARD, he knows (I mean, how could he not) that the kid is not his and I think he really loves Lois and just wanted to be there for her and the child. He is just a nice guy. He knows that she loves Superman and he probably has no chance against him but he just wants to try.
As for a sequel, we know a couple things:
1 - Superman has lost his K. heritage and cannot use the fortress due to the crystals being in space.
2 - There is A TON of Kryponite at the bottom of the Ocean. Tons of it fell off New K.
3 - Lex cannot be the Lex we want (ie: head of a major corporation with tons of money) because both SUPERMAN and LOIS can testify that he made NK and almost whiped out the US.
4 - It appears that SUPERMAN would want the world to think that the kid is RICHARD's because he would be a target. I also get the impression from the movie that Clark respects Richard. Lex clearly knows and that will come into play.
Just my thoughts,
DN