So. The meal plans. Here's the sitch. Swipes can be used here at Barnard and also in most of the Columbia dining halls (though sometimes with restricted hours). Barnard 'points' can only be used here at Barnard (Liz's place/2nd floor dining hall). For points you can use all over the place you will need to SEPARATELY purchase 'Dining Dollars' or 'Flex' (Flex can be used at some of the restaurants/grocery stores in the area).
If you cook for yourself a lot and always have cash/credit on hand, a large meal plan is not necessary - all the points are dollar for dollar and at most places they will take either your ID or regular payment methods. The main question is how many swipes to get and if you like only having your ID on you. If you are a dining-hall-meal-getter, figure out which meals you eat there and then calculate how many per semester you would need.
Official help links are:
Columbia dining breakdown -
Barnard Dining Breakdown -