Need to know a few more things. How many days, which hotel, how many souvenirs? Will you have a car or towncar service to get to your hotel?
For tipping, we usually leave mousekeeping $2 per day.
If breakfast and dinner are included, you may want to plan a lete morning breakfast and an early dinner and skip lunch some days. You really keep busy and 3 sit down meals a day really cut into your touring time.
If you plan on lunch, what do you plan on? Sit down or counter service? Check Deb Willis's site for menus. That will give you a good idea of food costs at Disney.
Menus
You can spend any amount on souvenirs. There are very expensive collectibles down to tshirts to markers. What do you want to come home with?
There are also things on sale in most stores. I can usually find tshirts or sweatshirts on sale. I have also found bags, and clothes on sale. I bought a leather jacket and a pocketwatch for my husband last year. (A $350 jacket - final sale price wirh AMEX 15% discount $153)
Best advice is to set a budget for souvenirs that you can live with. It is easy to buy lots of stuff!
Water is very expensive in the world. If you can stop somewhere and buy water you will save lots. (Water runs $2.50 a bottle)
Good luck!