*Looks around empty room*
Huh. Not sure why no one replied to this. It's an interesting topic.
My FIRST thought on this is, hey, man, let's drop out the names here, yeah? No need to go embarrassing anyone.
And to answer some of the questions that you posed, I would say I agree with you to an extent. I am personally someone who prefers to find out about a character through roleplay in the same way that you listed above. Generally, if someone starts telling me all about there character when we are NOT in-character, then they can come off a little self-centered and too focused on their own characters. In moderation, it's no big deal, but demanding things like that out of character is cause for a good, hearty, old-fashioned "No."
However, I'll make an exception in that point by saying that I'd like to know the powers of the others' characters when there is a battle/something that can harm or affect my own character. Say my character Stacey is normal, and does something stupid and picks a fight with John, my friend's character. I don't want to know John's power until John is going to attack Stacey. If his power is, oh, I dunno-- Firebreathing, then it would be up to John's owner to say, "Hey, Haru, mind if Stacey gets burned into a charred crisp?" I'd like to know in advance what will happen to my character so I can decide if I want to let it happen. If John's power was planet-eating and moon explosions then, uh, yeah. I'd go ahead and put the brakes on it.
Ya feel me?
But yeah, you brought another topic altogether in asking since when do we care about how powerful a character is? In a sense, we don't. This isn't a competition, and it's not about who can make the strongest, most badass, most evil, or grittiest character there is. I love the kind, the quiet, the mousy, and the fearful types just as much. However, there is a certain degree of need-to-know when it comes to the power of another person's character.
And I don't mean "Hey, yo, on a scale of 1-10 my character is a ten hurr durr." No, don't go saying it, because as you said, no one OR their grandmother gives a shit. Power is proven through action and ofreputation-- Something YOU can't build, but your character does. But the need-to-know basis of a character's power (especially a malevolent one) is in that other people need to be aware when their character might be harmed. NOT the characters knowing, but the USERS.
So when your DA friend wants to know the powers of your character, to some extent, that's a little too prying. But, in another sense, they might simply be worried that you would use your character's power too eagerly and hurt their beloved So-and-So. The best way to approach that situation is say, "Hey, I know you're curious, and I like that. Please, just give me a chance and let's RP it out. I promise I won't attack or harm your character without your consent. Here, I'll make the first post."
See what I mean?