Okay, you and others are right about Shinigami actually trying to tell Black Star about Angela, I forgot that bit.
On Kid: Yeah, his soul would be worth a lot, though I don't think it would be one Shinigami would relish collecting if anyone was stupid enough to kill Kid. That'd be a
great way to get judged by Death himself.
On the topic, I'd quite like to see how Shinigami would react to Kid getting into serious trouble. There's a suggestion he does worry about his perfection-obsessed son, but we don't know much about their relationship (other than utmost respect and loyalty on Kid's part).
I think you have a point about the second fight with Black Star showing Kid fighting seriously. In both cases it was a step up from their first fight, Black Star because he'd improved, and Kid because he, for the first time, he seemed to see the 'ninja' as a threat. And even
then, it didn't take much for him to bring Black Star down; very neat and tidy. If by 'neat and tidy' one means 'smashing poor boy's face into ground'. That was cringe-makingly
nasty of Kid. He proved a point, but even so...