Blaming differences

I want something like a product of diff and blame. I want to see some kind of "blame" output for each line of "diff -U0".

I tried something like this:
   git blame $changed_files

Is there such a command already?

I'd also like to do something of the inverse operation:  I want to
find commits within a range whose changes are NOT in some other
commit.   So, say I have these four commits
   A---B---C---D

Where D was created by 'git revert B'.
I'd like to find out somehow that this is equivalent to
   A--C

So that if I remove B and D completely, the with just A and C will get me to the same end result.

Something like 'git list-contributors HEAD' which would show me A and C, since these are the only commits that appear in any 'git blame $any_file'.

Do these tools exist?  Is it too expensive?

Phil