sim card for holiday in Italy to text/call Italian contacts while I'm there

Hi, I'm an O2 pay-as-you-go customer. I'm going to Italy for a couple of weeks. As I have a lot of friends there I will want to call and text them.

So I'll need an Italian pay as you go sim and I'll need to have my Italian friends' numbers on the phone memory (and then text them my new Italian number) -- I guess... is that what people normally do?
(and maybe change back to my Irish sim in the evening to check for messages/missed calls to my Irish number...)

The last time I was there, on my Irish sim, I made/received a lot of short calls and lots of texts. It cost me too much money and my Italian friends were paying about 50c to send me a text too.

- is there a particular Italian network that anyone can recommend (I couldn't find "O2 Italia" online)?

At some point I'll be living there for long periods and I'll want mobile-internet for ipad (probably a bill plan) as well as an Italian mobile phone... so, I'd like to start off with a company that I'll then stick with (and keep my new Italian number)

Any tips and advice appreciated , I've not done this before.

Dave (in Cork)