What is the nesting period of the European Turtle Dove in middle to southern Italy?
I think it would be difficult to answer except people living around or visiting frequently the Naples region as the bird distribution covers the whole central Europe during summer time.

Then my answer will focus more on the italian part. 

One interesting reading would be this document from the European Commission. 
Disclaimer: this document refers to biological aspects of the turtle dove, but the main topic is the pressure of the hunt on that bird. 

In page 10 they mention that: 


  Stable populations are found in central Europe: Italy, Austria, The Czech Republic and Slovenia (BirdLife International 2004a).


Page 14 table shows the period of migration and breeding countries (EU 25 only).

And in page 17, they shows that probably between 200'000 to 400'000 breedings pairs are present in the whole Italy (Estimation by Birdlife International)

Here are some refrences:


Breeding and distribution at IUCN
Distribution at avibase


As you can see the distribution os quite large and the figures of estimated breeding pairs very large. 

You can also check the observations (not only breeding) with that avibase link.

For the probability to nest the same place, I would say it's possible as in general the birds can go to the same place as the previous year but I cannot say more if the European Turtle Dove have a different behaviour or not. If they have a quiet place where there are no disturbance (Hunting, human activities) or predators, they would probably come back to the same place.