Regarding Batman killing...
I really don't have a problem with it, as long as it's to save Martha Kent. I'll be annoyed if it's just some pumped up mob bosses all at a meeting somewhere.
If killing a few people means Bruce's 'knightmare' doesn't come true because Martha Kent survives than that is absolutely fine. More or less the same as Superman killing Zod, killing some people to save the lives of many. As Spok would say "The needs of the many outweigh the needs of the one"
Not to mention, he's probably taking on a more personal approach with it being Martha Kent, mother of someone who he just nearly killed in their showdown.
but that's just me...