Kills

It's counted as a kill for the killer, but not a death for the unfortunate person until they actually give up or die.  Seems fine to me.  Only place it's a bit wacky is in TDM, where revives don't provide any relief on the scoreboard.

IMO should be a separate column for dons but revived. 

No idea, but is good for people who care about their stats and keeping the kd up, and hey if i (a support) get less teammates immediately giving up i see that as a good thing

I assume this is to deter people (who care about stats), from trying to quickly exit out when downed