France uses the euro. Currently, one U.S. dollar is equal to .88€, but it fluctuates often. Check Oanda.com for up-to-date exchange rates.
In France, the ATM is known as DAB (Distributeur Automatique de Billets). Wait until you’ve landed to withdraw money, as most stateside exchange rates have heftier premiums.
Aim to make most purchases on a credit card with a zero percent foreign transaction fee. That minimizes fees per swipe and any extra fees you’d incur from exchanging cash.