Some of this is naggingly familiar with my DS (8)
At school, and church, and at family/friends, he's all sweetness and light. But as soon as we come home and he has to tidy his room, or read a book instead of play a computer game, or clean his gerbils out, it's like I've asked the world from him!
DH and I often experience shocking back-chat from him; he'll nit-pick about how he didn't win such-and-such a game, how Dad cheated, how the dogs put him off, how he needs "me time" away from DD (WTF?! He's obsessed with her! But they do share a room, so play-space is limited). DH/I try to nip it in the bud, but how dare we?? :o
Then it starts... the boo-hooing, and the "you're not listening to me" followed by further howls. Then stomps into bedroom, and is alternating theatrical boo-hooing with long-winded speeches to his bedroom wall about how DH and I are terribly mean to him, nicely rounded off with the odd fit of coughing.
Note: he's in perfect health, there is no cough to be found when he's making DD laugh, charging round the house at top speed, bouncing off the walls etc 
DH and I are tearing our hair out, as we want to do so much with him (music lessons, swimming lessons, football clubs), but are unsure of how to proceed with this behavior.