The official language in Greece is Greek. Ancient Greek is now extinct.
€25 is approx $38
The time zone in Greece is Eastern European Time (EEST)
A pint of local beer in a taverna in Greece will set you back around €3.50 (approx $5.43), and is often less on the party islands.
Go fully authentic with meals from markets and street stalls, which is also the cheapest option: it'll cost less than €10 (approx $15) to fill your bellies there.
You can walk around a lot of the smaller cities/islands, but if you need to catch public transport, a one-way ticket only sets you back around €1.40 (approx $2.17). Ferries across to the islands can cost between €4-€10 (approx $6.20-$15)
Taxi tariffs start at around €3.50 (approx $5.40) and they add about 80c (approx $1.24) for every km.
Travelling solo or on a budget? Grab a dorm bed from €13 (approx $20 a night) or a domatio (Greek B&B) for less than €60 (approx $93).
Willing to splash out a bit more on your digs? A double room in a mid-range hotel costs between €60-€150 a night (approx $93-$232)