As with many questions, the more complex your requirements, the more complex the tool you need to deal with it. XML::Simple may do some of this, even possibly all of it. But whether it will work or not really depends on the structure of your document. Complex documents aren't handled, simple ones are, however, trivial. That's just the tradeoff.

I first had to use perl with a complex XML document. So when I investigated all the options I could find at the time, I found XML::Twig, and found it could do everything I needed. I believe it can do all of the above, although I'm not sure how much of your XPath requirements it will meet - it's got good enough XPath support for my needs, but I can't tell if it'll meet yours.