I know that DiveSicily Diving & WaterSports Center is in Taormina, not in Catania. Are you going to Catania? Or other places close to Catania?
In any case, you can contact my friend Salvo (his name) at
info@scubacademy.com. Give him my nick name: I've already told him about the possibility of your interest.
Please, find here the link to their web page. In italian, sorry.
About your questions:
In Italy we use mainly steel tanks: this is true for Salvo too.
Not a lot of surf with shore dives.
The water is now about 16 °C (about 60 °F).
You don't need any DIN adapter: the pillar valves (is it the right name?) of the tanks are DIN.
Probably the .5 mm wetsuit is a little bit "light": in any case don't worry. They will rent you everything you need.
Ciao,
A.