Yes you will need passports. Even though it is a Disney park, it is located in France, so any travel outside of the USA for you a US Citizen needs a passport. This website should be the first thing you should read, it will have all the information required for you get a US passport
https://travel.state.gov/content/passports/en/passports.html
Yes as
Disneyland Paris is located in France, you will need French currency, which are Euros - € You will need to talk to your bank about changing cash US dollars into Euros. You will also need to talk to your bank about foreign transactions fees and and about using your credit cards and bank cards in France.
Planning to go to Disneyland Paris is very like planning any trip to a US Disney Park
1. Decide your budget
2. Decide when you want to go
3. Book flights
4. Book hotel and park tickets
5. Book transport from airport
6. Book ADR
7. Enjoy Disney
Book Flights
The airport you need to fly to from USA is the main airport in Paris which is called Charles de Gaulle Airport. I use
www.skyscanner.com which is a flight comparison website to check the best flight prices and times. You can either get a direct flight to Charles de Gaulle or do layovers, depending on prices and whether your local airport flys to Paris.
Book hotel and park tickets
Like the USA parks, Disneyland Paris has both onsite and off site hotels. Most people stay onsite, there are 6 hotels with different budget options. There are also 5 offsite partner / good neighbour hotels as well as hotels in the nearby village called Val d'Europe. It depends on your touring style and budget, just the same as with WDW and DL.
The only thing you should be aware of is that if you book a hotel either an onsite hotel or a partner / good neighbour hotel through the official Disneyland Paris website you are actually booking a hotel and park tickets package. Park tickets for both your arrivial day and departure day are included in the quoted prices on the website.
Another note about booking or checking Disneyland Paris prices online. You can check / book through any of the country websites, you dont have to just use the USA version of the website. Each country has different deals and prices.
Book transport from the airport
Just like with the USA parks, there are various shuttle bus companys which provide transport to the park. Again it depends on your personal preference, some people use the shuttle bus, some people get a car service, some people get the train
Book ADR
Like Disneyland California, ADR can be book from 60 days in advance. However there is no online booking system, you must telephone the Disneyland Paris Dining Reservations call centre
Disneyland Paris does not have Magic Bands or Fastpass plus. Fastpasses are the legacy paper ones and you get them at the machines besides the rides