There is no "de facto universal currency". Technically the most probably de facto universal currency is the Yuan used by more than 1/4 of the worlds population. The US Dollar is much less.
Dollar
The currency used is the same one as most of the European Union countries: The EURO!
Euro.
There is no such thing as a euro dollar. What you are referring to is the euro, which is the name of a currency used in 17 of Europe's countries.
No. Canadian dollar.
There is no such thing as a "German dollar." The currency of Germany is the euro. As of the current exchange rate, 1 euro is equivalent to approximately 1.18 US dollars.
The currency of Italy is the Euro; there is no such thing as an Italian dollar.
Irelands currency is the Euro, which is stronger.
Dollar and Euro
There is much speculation about a possible universal currency for the world, but there are no plans fur such a thing at this time. If it were to happen it would likely be either the US dollar, or the Euro; or some new currency derived from either or both of them.
As of today's date which is August 18, 2014 one Euro is equal to one dollar and thirty four cents. The Euro is the currency which replaced the currency of several European countries.
No. The "Pound Sterling" is the currency of Great Britain (GBP). The "Euro" is the combined currency of the European Union. See Universal Currency Converter link