€ Euros. Banks do not normally exchange money, but post-offices will. You can also use Bureaux de Change but it's worth checking the commission and exchange rates as they are not heavily regulated and charges and rates can vary wildly. ATMs are widespread and usually offer better rates than exchange services, but do normally charge a small fee.
French. English is spoken at the main tourist attractions but in other places Parisians tend to respond much better if you try a little French before resorting to English. Young people speak more English than the older generations, but there is a high emphasis on manners so being polite will get you everywhere!
+33 for France and then 1 for Paris
Valid UK passport