How can I get Civi CRM to display the currency in reports and so on
Oh it's defintively available in a report - let me get to my desk and show you an example;

Install: Extended Report Extension: 
Got to your Adminster -> System -> Settings -> Manage Extensions -> Add New -> ExtendedReport (nz.co.fuzion.extendedreport)

After you've installed it -> go Administer -> CiviReport -> Create New Report from Template and select e.g. Extended Report - Contributions with Price Set data

Voila - there is your Currency -> I've checked it to show you where it lives: