In spite of the common cliché, your experience can result very different.
HITCHHIKING IT IS NOT ILLEGAL! except standing along the motorways (or high speed ways, "strade statali a scorrimento veloce") which, thumbing or not, is also illegal in most of western european countries.
Usually thumbing on the roadside, ramps, etc is not really successful; Italian people have a mixture of fear and prejudice which often don't make them stop easily if they are already running. With tons of patience (similar for Spain, Portugal and Greece) though, you might probably meet the best of locals.
Asking in the gas stations is generally the best solution. If you speak Italian and know local manners it might be very quick (e.g. in February 2014, Fede crossed the whole country from Milan to almost Sicily in less than 2 days, never waiting more than 15-20 min, chilling, freelancing using autogrills wifi and wild camping in service areas); if you don't, often being a foreigner helps and people might trust you and help you out just because of that.
Slow, local trains are much cheaper than fast trains, and usually very easy to blackride, especially for foreigners who won't ever get any fine.
If there's no way around it, you can simply dodge the fare on local trains. Conductors usually can't articulate anything beyond "Money" and "Ticket" in English, so just tell them "No money, no ticket" and they'll let you be -- in the worst case they'll ask you to leave at the next stop and you can resume hitchhiking or take the next train. As local trains are taking a lot of stops it is advised to take some of the express/high-speed trains between bigger cities. These trains are travelling really fast and even if you are asked to leave the train, the next stop can be 100-200 miles away so you can cover this distance at no cost.
Wild camping is illegal but mostly tolerated even by authority in case of short stay and not disturbing behavior.
In mountainous areas you may want to search for some "bivacco" (to be read bee vah ko) which are basically mountain huts (not always) open in case of emergency, instead of "rifugio" (ree foo joh) which is practiacally a mountain hotel aka paying refuge. Ask firstly the local community cause in case of storm you really don't want to find it closed.
In areas like Puglia people are so friendly that you can just basically ask if you could crash at their place if you need a place to sleep. In the South, you might also be invited for meals. Table-diving is good at service stations, at least in the North.
Usually not so cheap but very good.
Dumpster diving and skipping do work fairly well, both in supermarkets and openstreet markets. The concept, even if more and more spread among young/politically engaged environments, is quite unknown to authorities and food businesses->i.e. rarely you'll find a locked dumpster and very often you'll be offered food just searching among the left overs.
Vodafone sometimes has a special deal, 5 euro for a SIM plus 10 euro for a one month package.
Similarly to other Meditterranean countries like Spain, Portugal or Greece even if it's eurozone the wages are definitely not the same as central/northern Europe, meaning 2€ coins and banknotes are usually a bit harder to get.
Busking works pretty good though.
The legal situations do differ a lot according to the city.
You have very welcoming cities like Milan (where you can easily register online and book your legal busking spot for free), Ferrara (hosting every year in summer a "buskers" festival), Padova or Bologna. And other touristic annoying cities like Venice or Rome where apparently police can fine very badly and even confiscate your money and (much worst) your instrument, Barcelona style.
From the Austrian Südtirol to the very Mediterranean Sicily, the language, habits and manners of locals change significantly, sometimes giving the impression of having completely changed countries, if not continents.
The Italian language belongs to the Romance family and shares some 89% of vocabulary with French (totally different pronounciation though) and some 82% with Spanish. This means they can be mutually intelligible, at least concerning basics, for many Romance natives or speakers.
Italian people don't usually have good skills in foreign languages, however.
To find ecovillages and interesting alternative realities the R.I.V.E (Italian Ecologic Villages Network) website is quite useful, here a very helpful list of some of dozens ecovillages of the country.