Paris public transport?

Travel Info
We (9 people) will be in paris for 4 days in april (02-06). We will be staying in the center of paris, and we will need to go from/to charles de gaul airport, disneyland(for whole day) and parc asterix(also for whole day). What is the cheapest way to go around?

Travel Tips

1)Parc ast茅rix :

M茅tro / RER
ligne B3. Get off at Roissy CDG1 and take the Parc Ast茅rix shuttle (platform A3)

Cars Air France from Paris city center :
Line 2 : Departure from Etoile (Place Charles de Gaulle 鈥?Etoile) or Porte Maillot (1 avenue Carnot ou rue Gouvion St Cyr)
Line 4 : Departure from Montparnasse (Rue du commandant Mouchotte) or Gare de Lyon (Boulevard Diderot).
Get off at Roissy CDG1 then take the Parc Ast茅rix shuttle (platform A3)

2) DisneylandParis :
Regional travel facilities (Metro/RER)
From Paris, the RER line A4 (Regional Express Railway) takes you quickly to the heart of Disneyland Resort Paris... In just 35 minutes, you can be at the gates of a fairytale land where all your dreams come true!
Just get out at the end of the line, Marne la Vall茅e/Chessy station, 100 metres from the gates of Disneyland Park.

3) CDG airport :
Leaving Paris-CDG
RER B
- Terminal 1
Take A茅roports de Paris Shuttle Busses (line 2) gate 22, departure level until Roissyp么le-Terminal 3
- Terminal 2A & 2B
Take A茅roports de Paris Shuttle Busses (line 3) at gate 8 of terminal 2A and gate 6 at terminal 2B until "TGV/RER "
- Terminal 2C & 2D
Follow "Paris par train"
- Terminal 2E & 2F
Follow "Paris par train"
- Terminal 3
Take the footpath (about 250 m ) and follow "Paris par train"
A茅roports de Paris Shuttle Busses.

RER D
Access to RER D possible from Roissyp么le Bus Station. Take CIF bus no. 32 until Goussainville station.

Bus
- CDG-Roissypole > Gare de l'Est railway station
- CDG-Roissypole > Nation

Free A茅roports de Paris shuttle buses leaving from Terminals 1 and 2 will take you to your stop at Terminal 3.

Have a nice trip in my country ;) Source(s): http://www.parcasterix.fr/v2/default.asp...
http://visit.disneylandparis.co.uk/how-t...
http://www.aeroportsdeparis.fr/adp/en-gb...

Other Travel Tips
Definitely take the Metro. It runs directly to/from Charles De Gaul and to Disney. It's easy to use and cheaper than a taxi for sure!
Between the Metro (subway) and RER (regional light rail) you can get everywhere on your list. You can find English-language information at http://www.paris.org/Metro/. If you will be super-tired when you get in, you might consider hiring a van to take all of you and your luggage to the hotel -- can be a blessing after a long flight. After that, I'd take public transport everywhere in Paris -- it works very well.

Take a look at Carnet tickets which you can get for unlimited Metro rides over a set number of days -- as I recall, you can get 3-day and 7-day versions.

I've never ridden the buses -- have to do that next time.

Have fun!
ratp.fr ou sncf.fr