For those of you who aren't slavish addicts (curse you, Andy!), I'll put this behind a cut, so you don't have to be bothered.
First, you can give Lamb depth, but you can't make me like him. I think it's interesting that, rather than bring the Manning family's derangements out into the open by taking Duncan and Veronica down to the station and starting a formal investigation (especially since Mr. Manning wanted them prosecuted fully), with all of the scrutiny that would entail, he instead chose the side of the road dumping route. For one thing, their story is easily provable, with the paper trail Meg left on her laptop and whoever the social worker on the other end is. However, Lamb being Lamb, he's not willing to endanger his voterbase (and possibly a future source of bribery incomes?), even for personal scruples, even for something he once went through his own self.
And my personal opinion of the timeline of the abuse WOULD be that the recent tragedy in the family from the bus crash had brought things to this head, but Meg's emails predate the crash (obviously). Perhaps the closet thing is a recent development?
Interesting that Meg felt it was necessary to communicate with CPS over Grace, but was either unaware of, or didn't want to get involved in, the strangeness of the Goodman household. Man, is there even one normal family in Neptune? Maybe when your household income hits a certain level, the psychosis fairy pays you a little visit.
One more thing. I honestly can't tell, just from the timing (character readings are just too skewed for me to be certain), how long Kendall was in Duncan's room. I mean, Logan had time to be dressed and out on the couch, but he already had his shirt on (what about his pants?) when he sent her packing from his room. It could have just been the time that it took for her to disrobe, Duncan to see her, send her packing, and then to put her clothes back on. I wish there was some other indicator.
Just my personal opinion? I think there’s some link between the way Duncan looked when Veronica passed along the info about Meg and ‘that boyfriend’ that she had over while sitting and whatever was in that envelope Duncan pulled out of the air vent. Or, at least, whatever he thinks was in that envelope.