I would definitely recommend at least sealing your doors. Doing your trunk (quite a bit of it, if not all) will show great results. I just got a pack of the newer raammat bxt II to do my hatch and doors, but my car is smaller than yours. The bstock bxt would be a good idea, it's a pretty sweet price.
x2 on the brakes though. If you vehicle is having issues with what makes it stop, how it sounds is a minor detail.