Liszt Ferenc Airport is the major hub in Hungary, but even Vienna airport is close to the town of Sopron.
From Liszt Ferenc, the best option is a 200E bus into the centre of Budapest, then a train from Budapest-Kelenföld station direct to Sopron. Trains depart every three hours and have a journey time of just over 2 hours. The whole trip will cost a little less than €20.
Children are welcome at VOLT, with those aged 11 or under entering for free. Children aged 14 and under must be accompanied by an adult at all times.
Yes, there will be ATMs on the festival site, as well as in the town of Sopron.