What would you say to the pope, if you had eight minutes of his time? That's a question the Taoiseach Leo Varadkar is having to ask himself, ahead of his private meeting next weekend with the leader of the world's 1.3 billion Catholics.

After landing at Dublin Airport, and a quick visit to Áras an Uachtaráin, Pope Francis is due to arrive at Dublin Castle to meet the Taoiseach.

The diplomatic niceties have been signed-off: Mr Varadkar will speak first for six-eight minutes. The pontiff will then reply for up to eight minutes. Then it will all be over, and Pope Francis will depart for the next engagement on his 36-hour visit to Ireland.

When the pope’s visit was confirmed earlier this year, Mr Varadkar said: "I look forward to meeting him during his visit."

Now that the meeting is almost upon him, what is the Taoiseach going to say?

We do know that Mr Varadkar is supportive of the visit, saying: "I think the visit is very welcome... I'm very pleased that he's going to be saying mass in the Phoenix Park... and you can see the huge interest from the general public."

Yet Pope Francis is arriving in Ireland for the World Meeting of Families amid huge controversy surrounding a Pennsylvania grand jury investigation into clerical sex abuse which found "credible allegations against over 300 predator priests".

And Mr Varadkar has already declared he will raise the issue of abuse in the Catholic church. The Taoiseach said he would express: "The real concerns that the Irish people have... in relation to issues such as the church's involvement in Magdalene Laundries, in Mother and Baby Homes, in sexual-physical abuse."

But, how far will he go? For example, will he raise concerns expressed by abuse survivor Marie Collins that the Vatican statement on abuse in Pennslyvania, like previous statements, "falls short" regarding holding those who enabled abuse to be held to account?

Last May, the Taoiseach told the Dáil that it "might be the most appropriate thing to do" for Pope Francis to meet survivors of clerical sex abuse here.

Only this week, the Catholic Primate of All Ireland, Archbishop Eamon Martin, said he would be "surprised" if such a meeting didn't happen, adding that any apology from the pontiff "needs to be more than [saying] 'we're sorry'". Might the Taoiseach have any advice for the pontiff on what to say?

One of the most visible changes in society here, in the nearly 40 years between the two popes’ visits, is the fact that Ireland has its first openly gay Taoiseach. Mr Varadkar campaigned in the Marriage Equality Referendum. Same-sex marriages are something Pope Francis opposes. That said, the pontiff has adopted a very different, more inclusive approach than that of his predecessors, saying: "If someone is gay and is searching for the lord, and has good will, then who am I to judge him?"

Might the Taoiseach suggest that the Pope Francis institute further changes? Mr Varadkar certainly will not go as far as former President Mary McAleese who this year described the Catholic church's teaching on homosexuality as "evil" and said that the church's attitude to the LGBTI community was both "unchristian" and "worse than uncharitable".

Mr Varadkar has, however, made it clear that this is a topic he wants to speak about, given that the World Meeting of Families is happening in Dublin, saying "... as a society and Government, families come in all sorts of different forms, that includes families that are led by same-sex parents and one-parent families".

One subject which seems far more likely to be avoided is the recent call by Culture Minister Josepha Madigan for women to play a greater role in the Catholic church.

This followed her spat with the Archbishop of Dublin Diarmuid Martin over leading prayers in her local church, when the priest didn't turn-up. Afterwards, Ms Madigan said bluntly: "I think the Church should be ordaining women. I think it should be optional that priests marry."

She also said that she would raise these issues with the pope if the opportunity arose. From the Taoiseach's perspective that issue may be best left for others, such as Josepha Madigan, to raise.

We know that Mr Varadkar had hoped the Pope would be able to visit Northern Ireland during his visit. He expressed his wish to the Dáil last September that "the Holy Father" would make the journey as it didn't happen during the last visit 40 years ago.

He said: "Unfortunately, when John Paul II visited Ireland he was not able to travel North and made his plea for peace from Dublin."

But given that Pope Francis is not travelling across the border, and some politicians from Northern Ireland will also be in Dublin Castle, he may opt not to.

It's not all going to be one-way traffic. The pontiff could also raise a few issues himself.

For example, he could inquire about the Government's decision in 2011 to close the Irish Embassy to the Vatican. One Vatican source, quoted by the Reuters news agency at the time, was "extremely irritated" by the move.

A few years later the embassy reopened but was a slimmed down version.

Given the Government has announced a plan just a few months back to double its diplomatic presence in just seven years, the pontiff might inquire if the decision to close its Vatican office could be re-visited.

He might also ask about the Government's legislative plans, following the referendum to remove the Eighth Amendment from the Irish Constitution.

The outcome, which secured the backing of more than 66% of those who voted, is another indication of the dramatic changes in Ireland in just under four decades. In 1983, 67% had voted in favour of inserting Article 40.3.3 into the Constitution.

With the clock ticking down to the meeting, both Mr Varadkar and Pope Francis will have to finalise their approaches.

Then it will all come down to two men, sitting on two chairs, for around 16 minutes. Whatever about what comes out of the meeting, it will undoubtedly be one of the most high-profile events of the Taoiseach's term in office.