In winter you must use wetsuits (5-6 mm or more), in summer you can use 2-3 mm or short wetsuit, or if you prefer you can avoid to use it at all. You can really kite all over the year, but the best months are from April to October. During the winter you must only be careful about the very cold water.
Verona airport is 60 km far from the lake. You can arrive at Milano airport and the go to Brescia and you are 25 km far from Garda Lake. Then you've also lots of train and bus connections all over Italy. There are ferries to cross the whole Lake. The highway to major cities starts 20-40 km away from the lake.
There are rules by the local kite club. You have to pay 35 Euro per year to enter the beach but you have access to the rescue boat. A flotation vest is required.