Cheap and easy brake upgrade is to swap the NA caliper carriers for Glanza ones, this allows you to run the larger Glanza discs. Put some decent pads on and that's all you need for an NA. Braided lines are good too.
There should be an unused plug taped into the loom under the drivers side plastic in the boot. This plugs straight into a plug on the parcel shelf from a CD spec UK car which had rear speakers as standard.