Best amount of time is probably 3-4 days depending on how you like to do a Disney Resort. Stay on site (if money is no problem) for extra magic hours to maximise your time in the parks or stay in Val d'Europe which is 5 minutes on the RER (the next stop) for much cheaper accommodation (can be of better quality too). If you do want to stay on site then bare in mind that Newport Bay is under heavy refurbishment. The official hotels do come with entry in to the parks too so weigh up all the different pros/cons and costs before making your decision.
Food wise is all down to what kind of thing you prefer. My favourites are Walts and Blue Lagoon. Walts tends to have slow service and is pricey but the food is phenomenal. Blue Lagoon is amazing because of it's location in Pirates of the Caribbean, the food is also fantastic. The new Ratatouille restaurant looks great but has limited options so isn't for everyone.
The fast food is of varying quality and although most complain about the high prices they are similar prices to any theme park food outlets in Europe.
If you're looking at checking out Central Paris then stay for a few nights a bit closer to the center and have a good idea of what you want to see and do and how to get around.
RATP.fr is a great official website for info on how to get around on public transport.
If you're used to WDW then Paris will be very different for you, everything is right next to each other, a 5 minute walk between the two parks and the Village. Definitely check out the attractions that are unique to Paris like Phantom Manor, Pirates, Casey Jr, Space Mountain: Mission 2, Cinemagique, Animagique, Ratatouille, Crush's coaster and Tower of Terror (although they're all very similar I do have a love for the Parisian cast members on this attraction).
Some people find the staff to be rude, just provide a smile and say at least Bonjour and you'll find them to be very helpful. If they see you try to make an effort to speak their language they usually make an effort to give you the best service. I find using the phrase "Parlez-vous Anglais?" ("Do you speak English?") helps break the barrier.
I hope that helps a little bit, more than happy to delve into more details.
http://www.dlpguide.com/ is also a great tool and is full of useful information.