Tickets for disney you buy at the park entrance - no need to buy them in advance
For travel you need to get the RER 'A' ligne train from the central stations (e.g.Gare de Lyon, Chatelet-Les Halles, Auber,Charles deGaulle-�toile) to MARNE La VALLEE-CHESSY station (approx 100 meters from the DPL main gate). The travel time is approx 40-45 mins and about 15 euros return (might be slightly less).
We stayed at a fab hotel recently in Paris - just by the Tuilleries gardens and the Louve, basic but ideal for a couple of nights - its called the Prince Albert Louve hotel. If you google it there are plenty of sites listing it - this site is just one
http://www.hotelclub.net/DirectHotel.asp?hotel ID=16815&inYear=2007&inMonth=4&inDay=23&outYea r=2007&outMonth=4&outDay=27&x=36&y=10
As for the Jules Verne restaurant - I have heard mixed reviews since it was taken over earlier in the year. Another place to consider which has fab views of the tower is Les Ombres on top of Musee du Quai Branly. Or perhaps a Bateau Mouche dinner cruise at sunset.?