Where would you start?
 

Ok, so you (me=2013, 70K) have your FR-S with a bunch of different rattles from all sorts of different scenarios, instead of me trying to explain each one, I was thinking maybe I could just start upgrading/replacing some of the low hanging fruit which typically have problems anyway.

So, what would be your list of things to start changing in hopes that some issues might get resolved anyway, starting with the cheapest/easiest to fix and going from there?

First thing I would do is explain each one, find out which are normal, and which ones aren't, and prioritize.

The first thing I would do is find the most obvious rattle and fix it. Then I would find the next most obvious rattle and fix it.

Nothing can seem daunting like a car that sounds like a mechanical keyboard going over bumps and around bends, but as you'll start to eliminate the easiest ones, the others will become easier in turn, because you dont have 12 simulatenous rattles going on anymore.

Take off your door panels, gorilla tape on the radio buttons, air impact hammer on all suspension components, take out passenger seat, remove heads from block, take out short block, remove direct injection

Have a friend drive the car so you can crawl around and push on different areas to help pinpoint where the sounds are coming from.

Get a louder exhaust. And noisier tires. The rattles will disappear.

It is a 10 year old car that rattled when it was new so trying to tackle it now will be a challenge. Fixing one rattle is more than likely just going to cause another.
Just be glad you don't live where it get's really cold!

Totaled.