I'm afraid the gross pay at all bases is different, and even within some bases depending on how old your contract is. Ryanair has around 80 bases now, each with its own contract.
I can give you estimates, but they are just that and maybe plus / minus a few hundred Euros per month. In Ciampino or Fiumicino on a Ryanair contract you should expect to take home around €6000 net per month average across 12 months. This includes net basic pay and net sector pay. Both sector pay and basic pay are taxed, but they are taxed differently depending on which country you are in and even which routes you fly. In Italy, Italian domestic sectors are taxed differently from international sectors. You will probably fly around 90-100 hours a month from April to October and around 50-75 hours a month for the rest of the year.
In terms of annual leave, you will have one complete calendar month off with zero flying and this is likely to be in the winter. Additionally, you have 10 extra days off. You are correct that you get 13 days off flying by taking a block of 5 days. In the past it's been difficult to get blocks of 5 days off in the summer but the last couple of summers it's been much easier.
I hope this helps. Sorry I can't give more specific info. You'd have to ask someone actually based in CIA or FCO on the same contract for that.