Ahh, kitty names.. I can definitely relate to some of the things you mentioned here.
For example, "Wickedkill," I agree is, at first sight, fairly absurd.
Along with names like Depressionkit, Malevolentkit, Suicidekit, and any other profoundly dark names, it truly is unthinkable that a loving queen would lay such a harsh name on her helpless, blind, mewling kit who is little more than the picture of true innocence.
However, if you're really into that sort of name, I would imagine there'd be a serious story behind this name to explain how this otherwise blameless kit would have gotten such a name.
For example, maybe that kit was born to a Clan in the midst of its dark times, battle and woe (such drama much angst wow), and perhaps this queen had lost her last litter of kits, causing her to fall into a fit of mental instability? It is believable that an animal, let alone a bereaved, unstable mother could fall into such dejection that she'd assume even her newest kits would have no chance of life? She would love them and keep them, but could throw out a bitter name like "Lostkit," or even something as cruel as "Hopelesskit."
It's just an example, and might explain for some of these unusual names, if you play the story out right.
Or, perhaps it could be as simple as a kit who had a normal name, but committed some deed--intentionally or unintentionall--as an apprentice (since kits generally can't/won't do anything too heinous) that earned him a harsh name from a cruel or corrupted leader. Maybe it was like naming that cat "Betrayalpaw" as a constant reminder of what he did.
Dark, but... It could happen, again, if you play it out right.
I guess the main point I'm saying here is that if you're going to have an unusual name, I think a good backstory would be in order for it to really pack the same "punch."
As for Bisonstomp, I think that one is semi-believable.
Same with living near a zoo-- it would be odd to think a Clan would live near one, due to all of the cars and twolegs running about, but think about it.
Where there are people, there is food. Where there is food, there are going to be little varmints like mice and birds (pigeons and seagulls especially) who are ready to feast on the bounty of noms dropped by careless twolegs. Now, what's more enticing to a cat than unsuspecting mice and birds feeding, on the ground, in the open?
So, I could see a Clan finding their home, perhaps in a woodland on the backside of a zoo (if it's placed correctly, since some zoos are in the midst of forests, etc.), and coming out during slow hours to maybe snag something. Not to mention, it's likely that the zoo staff might appreciate the cats for staving off the population of pests (and by extension, other animals like local snakes that like to eat those mice) in the zoo. City warriors? That sounds kinda awesome to me. Plus, I would imagine their names might possibly reflect those surroundings.
Now, how would Bisonstomp have found his way all the way to the land of FeralHeart, and left his old Clan like so? It's hard to say. But, it is plausible if you play it right.
