Roster:
is 5/4 on the ryanair contract, floating people are on 5/5 but most likely you will not be offered this contract if you are looking at direct entry/cadet
Base:
when you start you will have a few choices usually offered to you, usually 3 choices and you can pick which best suits your situation, ie for commuting purposes which have the most flights to the base, or if you will stay in an area without commuting which suits your lifestyle best
Hotels:
You can stay in a hotel or find longer term accommodation if you prefer, on ryanair contract you generally won't be moved anywhere else,
Positioning:
It's up to you, if based in Italy, but live in France, you will have to jumpseat in uniform and organise which flights you take yourself to get there for the start of the block of 5 roster,
Hope that helps, all IMHO