Jesii of North Sydney

Is the plural of Jesus 'Jesuses' or 'Jesii'?

Anyway, there are three statues of Jesus along the Mount St plaza in North Sydney. One is Jesus in a technicolour dreamcoat, one is greyscale Jesus and the other is 'One Love' Jesus. I keep bumping into all the Catholics who stop to take photos with each of them.

I made the mistake of scheduling a meeting in the city this morning. The top of George Street was blocked to traffic. There was a pilgrim parade instead, which was worse because the crowd wasn't going my way. The parade featured pilgrims grouped in countries with the head of each group displaying their country's flag. It was like the Olympic opening ceremony for Catholics.

This evening I came home to find that the quiet suburb of Waverton had turned into a very loud concert of people covering bad music: CDB, Mary Mary, Mariah Carey and Guy Sebastian - need I say more? It ended with a ferocious fireworks display that I couldn't see, only heard. Fortunately all World Youth Day acoustic activity ceased about half an hour ago. Catholics need to sleep, after all.

Can someone tell me why this event is called World Youth Day?
1) It's not for all the world, only Catholics;
2) It's not just for youth - I would hardly call the Pope a spring chicken;
3) It's not for a day, it's for SIX.