There are two ways of looking at that. Ireland is a country, so there are no other countries in it. Ireland is also an island that has the Republic of Ireland on it, which can be just called Ireland, and also Northern Ireland.
Ireland
It's an island. The only country that borders the Republic of Ireland is the country of Northern Ireland.
Ireland is independent, so it is not ruled by any other country. Northern Ireland, which is different to Ireland and may be what you are referring to, is part of the United Kingdom.
England Wales Ireland
The euro coins look different on one side in each country that uses them, but they can be used in any country. The notes are all the same for all countries. So yes, you can use euros from other countries in southern Ireland, and also in western Ireland, eastern Ireland, the Irish midlands and the northwest of Ireland.
The Republic of Ireland and Northern Ireland.
No. The Shannon runs through Ireland and does not form the border between any countries. It does form boundaries between some counties in Ireland though.
There are approximately 43 countries in the world that are smaller than Ireland in terms of land area.
Ireland is part of the European Union and therefore 'Allied' with all of its nations. Ireland isn't really in any particular quarrel with any country at the moment, so in that sense it's Allied with everyone.
England shares a land border with Scotland and Wales. The nearest foreign countries are Ireland, France and Belgium.
Ireland comes in at 120th largest in the world out of 234 countries.
Ireland is an island so it has no bordering countries. On the island of Ireland you have the Republic of Ireland and Northern Ireland, which have a border.Well no countries border it directly as Ireland is surrounded by water, but the 3 nearest countries are Britain, France and Spanish. Of course if you're talking about the republic of Ireland then the country that borders it would be Northern Ireland