Remember that maybe you’ll be interviewed all day-even if you don’t realise-for example, by the person who’s picking you from the airport, the other PhD students during the coffee break and so on. I don’t want to put you under pressure, maybe it won’t be like this, but you should pay attention to what you say to everyone during the entire day.
Another thing: Ok, you'll talk a lot about you, but don't forget you also need to ask a lot of questions-about what is expected from you, the work being carried out by the group, other(funding, accommodation, etc.).
So in the end it’s not just you being interviewed, they are also being interviewed, you need to understand if the research group satisfies your needs (software, supervision, data etc).
Good luck!