Trying to determine where your ancestors came from, once you have an Italian birth certificate in your hands, you will see it shows the place of birth.
It usually is the adress of their family home, since they didn't go to the hospital to give birth to their child.
To find baptisme information, you need to know in which church the family did it. This is not easy, when you live far away, and even if you live in the same town!
I strongly reccomend you to visit your Arcidiocesi's web site, since it usually list all the churches in the area, and how long they've been active as a parish.
Personally, I'm happy with Genova's Arcidiocesi: their site www.diocesi.genova.it is detailed, and all churches have adresses and telephone numbers. Some of them also have pictures, or email adresses to the parisher!
There also is www.diocesi.torino.it which covers some part of Piedmont, and www.diocesiacqui.piemonte.it is about the area around Acqui.
Of course there is plenty of them, covering Italy, but those are the ones I know personnally.
Before trying to find a church on the Yellow Pages, perhaps you better try those sites!