1. I think like France you will need a Italian passport.
2. Road tax for anything with an engine over say 1300cc is huge!
3. Insurance to insure an Italian car in Italy i would think without licence impossible, but you can insure a Uk car in Italy without a licence.
Annual testing not sure
I kept a UK registered Range Rover for three years in France, without a problem, no tax no mot just insured it locally