To be fair Serie A won't be a bad champ for him to develop his skill. He have quite the backpack of ability with him and playing in the midfield you have will make him loose the habit he got to do a little too much by himself something that impede his game-play. So maybe not this years but the next you will have quite the player.
I think he's staying for sure. The only reason he's leaving PSG is (IMO) because he doesn't get to play while we offer him exactly that. I expect him to play some games here, just like Pogba did when he arrived (he probably influenced the deal too).
Not completely sure it's all about play time to be fair, last years he was only 17 so i think it's ain't uncommon and best for him to not play much and this years he probably would have had a good amount of game be it in Paris or in an other L1 side like Lille who were interested and when you see how well Lille is developing their players in the last few years it's not bad at all going here.
The true story is just that weather is so shitty here in Paris during the last 2 years that they just decided to go in a more sunny country to be able to do some barbecue every sunday.
Also, don't get too excited already. For every Pogba there's a Buoy.
I think you could for this one.