We were lucky to witness an erupting Etna the night after we arrived. Will never forget this experience. Bring a good camera and a tripod and spend some time on the magnificent roof terrace. And be prepared to sleep with the rhythmic rumble of a giant snoring dragon, with the occasional explosion as it whips its tail. You can see Mount Etna from every room above the ground floor, by the way, and even from your bed in the bedroom.
If you ever make the mistake of ordering a several-course meal (a "menu") in Sicily, which will get you three or four gigantic dishes, Casa Francesca will come to the rescue; it has three steep flights of stairs that will keep you fit during your entire stay.
There is everything you need to get cooking and three Italian coffee makers (including a huge one, which we used).
We never personally met Vincenzo (his very kind aunt welcomed us), but you can pretty much ask him anything and he's very flexible.