I saw Lana as turning to Chloe not just as desparation but as turning to someone who in the past has been able to help with weird situations. And we haven't seen a total break between them--I think in Lana's mind that probably happens after she overhears the Clark/Chloe conversation about killing Lex.

My reading of Chloe's reactions to Lana in that initial scene are somewhat different than yours, though. I saw her silence when Lana suggested Lex might be dead as shock more than anything else. (If Chloe wanted Lex dead, or secretly wished him dead, why on earth did she save his life in "Void"? I realize that she does later say that Clark might have to kill the vessel, but that's *after* the total destruction of the world's infrastructure has started. In that scene where Clark first says he has to kill Lex, she's the one suggesting that his dad is out of line for asking him to kill anyone.)

I don't actually think Lois has been wasted space--they're clearly positioning her to be a political player next season, probably to get her more involved in the mytharc. I agree that they're doing it a little slowly, but considering how rare it is for them to set up character development, I'm not going to complain.