1. our demo - can't you login as John Smith (admin) ? I can... I've forgot to add a Doe Jane to the accounting access group, so she can't view the exchange rate entries.
It's a permission issue to access Exchange Rate records. Access Accounting or Manager is required.
2. Tab under contacts - you're right that it shouldn't be here if you don't have permission to that.
I've fixed this. Update in the store - version 1.0.2
3. You're right, that it could be useful. Now companies are hardcoded. You could use "Custom customer billing" with new Invoices. I'll discuss this with our team.