hi, as you know we stayed there in june, I too had read about this deposit, but on no occaision did they attempt to ask for it, even when we checked in, the only thing they asked us for was one of our passports, this apparently is normal practice on the island, for registration purposes. The passport is held for 24hrs and then returned to you the next day!
Safe's are around 30€ for the week, but this is optional and we never bothered, not really wise on any holiday you take, but we felt safe there! (excuse the pun) I would more than likely of had a safe if my room was one of those which fronted the street, but even then it would take a monkey like thief to be able to access your room! The choice is yours! regards martyn