Hello,
KML (not KMZ) is text, so you don't need any conversion to that extent (try opening a KML file with a text editor).
As for CSV, you can use MS Excel if you have a reasonably recent version of it that will import XML files.
As ManoM said, KML is a type of XML; simply save as a KML (not KMZ) file, rename the file from ".kml" to ".xml" and then open it with Excel, which will convert it into a spreadsheet for you. Of course, you can then save as a CSV file if you want.

Cheers,
Simon.