Firstly I agree where you're coming from. Seeing just how surreal some of those twists have been in the past, this stuff seems a little bleak. I fully agree. As much as I was in awe of having a No.2 of the organization who is manipulative, calculative and down right lethal, after his reveal it's not the same. Maybe because he's just an old man or the character of Rum couldn't handle the expectations that were created prior. But since you asked questions, some points need to be made. Let me just put it out, these are my personal takes on your questions.

The grenade part is more on the side of creative liberty. As valid as your point seems an argument can be made that a grenade mid air blasted might/might not be that effective. A trope often seen in action movies/series.

Kir being the only one unscathed from the grenade would actually put her into danger, as someone like Gin will immediately jump to question her integrity towards the organization.

The camel vs BO chase is actually one of the most thrilling scene in recent DC. You gotta understand that BO were after him like mad, hungry dogs who were being instructed by Rum. A methodical, calculative man(atleast that's how he's shown). If it was any other situation, he could do it easily but this is a different situation. He won't be killed but tortured for information and that will be a big blow for a lot of things that just couldn't happen. Hence it was a priority that camel gets out from that alive. And it's not like nothing happened. Poor guy lost his long locks, have some sympathy for him.