What do I have to replace? Flex Pipe or more?

What is your question?

I have an issue where my Flex Pipe (and subsequent repairs) have rusted off, so my car is very loud. It is also missing the heat shield. Since I'm not a car person, I'd like a rough estimate/information on how much this should cost and what kind of parts I'm looking at. So do I have to replace just the Flex Pipe and hope it lasts more than 6 months? Do I have to replace one or two more parts, or do I have to replace the whole exhaust system? Thanks in advance!