I don't think (5) is called "democracy", but it sounds nice. Democracy is "everyone gets a vote", which devolves into a battle of populists. There's nothing in democracy that would guarantee the kind of accountability you are describing.

Besides, as soon as you introduce this kind of checking, you'll just cement the oligarchy. The winning strategy would be for a billionaire not officially in government to work their magic through a puppet with a clean tax report.