a) - I would say in general, yes, that's fine! Though with Chrollo he's got himself so controlled that a lot of his emotions just come through as various shades of calm, even when he's speaking more enthusiastically. Whether that's positive or negative shades of such ("I'm happy for you, I'm just not going to indicate through more than an honest smile" versus "I've calculated how to kill you with the objects in my pocket.") is situation dependent. And if he's feeling more strongly I'll indicate it in my tags!

b) - If it comes up, let's talk about it. I'm not averse, we'd just need to plan.