First of all, I think Jimmy's reaction to Lois and Sam is completely reasonable. It's not logical and it's not how he SHOULD feel, but unfortunately, feelings aren't always logical or "right."
Second, Lois and Clark talked

(that is sad, by the way.) But this is a connection that can be a foundation for a relationship.
When I read/watch/write couples falling in love, I want to see some kind of connection like this that says, "I understand you." It doesn't have to be monumental, but I need to see something that establishes a bond.
And as far as Lois being in love with Clark, yes she had feelings for him longer than this. And yes, Clark doesn't have feelings for her right now. It's sad, but unforunately, reaslitic. Not all people love the same person at the same time.
And (I said this in the "Learning to Love" FDK thread as well)YOU CAN'T FALL IN LOVE WITH SOMEONE JUST BECAUSE THEY LOVE YOU. (Even if Clark hadn't been still interested in Lana.) It isn't that simple. (Although, like I said before, if you're not careful, you can try to believe your in love.)
Oh, and I almost forgot to say this, but Clark is adorable with Christopher.