Warning don't really influence me or turn me away from anything. If something looks like it's promising, either from the summary or the first couple of chapters, I'll probably continue to read it.
What you said about not warning people about mild violence/sexual content if there's already a graphic warning makes sense. Why put both there? Because if you already have graphic stuff, chances are you're going to have some mild stuff...hmm..
When I was posting one of my stories originally, I was kind of hesitant to put the Death warning, just because my big surprise ending is that the main character dies (Aren't I nice?) so I was kind of iffy on putting that there... in the end I think I did, but it kind of worried me because I didn't want to give away too much, you know?