Monday is a great day to visit whether school is on or not, DLP crowds are nothing compared to the American parks so you should be fine. Keep in mind Paris and Disneyland are covered in snow right now so wrap up.
General tips for a trip to Disneyland Paris:
Disneyland Paris
Must Do attractions:
1. Phantom Manor
2. Big Thunder Mountain
3. Pirates of the Caribbean
4. Indiana Jones and the Temple of Peril
5. It's a Small World
6. HyperSpace Mountain
7. Twilight Zone Tower of Terror
8. Crush's Coaster
9. Ratatouille
10. Rock N Rollercoaster
Make sure to watch Mickey and the Magician show at Walt Disney Studios, Disney Stars on Parade [5pm] and Disney Illuminations fireworks [8pm] at Disneyland. Arrive at least an hour before show time to get a good spot for parades and fireworks. Oh and don't forget to find the dragon under the castle.
Park Hours:
Disneyland: 10am - 8pm [Magic Hours 8:30am to 9:30am*]
Walt Disney Studios: 10am - 8pm [Magic Hours 8:30am to 9:30am*]
*Resort hotel guests only
Fastpass is the old ticket system which includes the following:
-Big Thunder Mountain
-Indiana Jones Coaster
-Peter Pan's Flight
-Buzz Lightyear Laser Blast
-Star Tours 2.0
-HyperSpace Mountain
-Rock N Rollercoaster
-Tower of Terror
-Ratatouille
-Flying Carpets
Food at Disneyland Paris is very expensive and underwhelming so recommend strolling through Disney Village to McDonald's if you are on a budget.
Current attraction closures:
-Phantom Manor
-Casey Jr
-Storybook Land Canal Boats
-Sleeping Beauty castle walkthrough
Characters, shows, parade times and locations:
http://download.disneylandparis.com/Disneyland-Paris_Shows-and-Parades.pdf
There's the Disneyland day planning sorted for you, hopefully it will be of use. Tons of guides on getting around Paris online so you should be able to find those easily. Paris is very easy to get around if you used the trains and Metro. Also get attraction tickets online in advance as they are usually cheaper and will often allow you instant access and skip any queues.