Rich - Welcome to the CC. As Markus said, make use of the search tool, and you will get a great many of your questions answered without having to ask a single one. Take a turn through the
FAQ - lots of information about the difference between the two models and the options available for each. Look through the "complaints" forum to see what's not working - although don't let the information there get you down - by and large, the Cayman S and Caymans are good, reliable cars. Look through the "comparisons" forum... there's been several threads posted by former and current 350z owners... also, KS-CS's advice on test driving is spot on.
brad