Struggling with tangled

I am trying to sort out a tangled (in the sense that I several branches that split a long time ago, but are reasonably close subsets of each other) repository of mine using git rebase. I want to isolate the commits that cause the key differences so that I can then easily enhance the code but carry forward the variants (using git-rebase again probably).

I have some questions which are causing me some grief after merge conflicts. Can someone help me.

1) I often edit a merge conflicted file to the state I expect it to be in at 
the end.  This sometimes means that I edit it to a state where no change is 
seen.  git-update-index notices this and doesn't do anything, but when I try 
git-rebase --continue it won't because it says git-update-index has not been 
run.  What am I supposed to do then? [Is the answer git-rebase --skip ?] 

2) Some files get completely munged with conflict resolution markers every 
few lines.  Is there a simple way to say "don't use this file, but use the 
[stage2/stage3] sources of the merge". (ie one of the original inputs to the 
merge - and if so, which one is which) 

3) I sometime hit a merge conflict in a file which I know will actually be 
deleted at the tip of the topic I am rebasing.  Is there a way at this point 
to just tell the conflict resolution to say make this file go away. 

4) I repeat the question I asked in a thread above.  What is the --merge 
switch on git-rebase actually do.  The man page starts talking about merge 
strategies, but there already is a -s switch for that. 

 --
Alan Chandler
alan@chandlerfamily.org.uk