How exciting! There will be food booths all around World Showcase that open at 11am (maybe 10-15 minutes earlier if they're ready). Booths will close with the park and are not typically open for any extra hours. Lines will build throughout the day and Friday nights (and weekends) are typically pretty busy with a lot of locals coming in.
All items are available for purchase a la carte. Many years ago they did do a "deal" where you purchased a limited pass of sorts but they did that one year only and haven't brought it back.
The items are also served individually and there aren't trays like there would be at a quick service restaurant. That can make it challenging to carry multiple items if just one person is doing the ordering. Some people bring their own trays. They have sold a small festival themed tray in the past. Last year I bought an inexpensive set of foldable, fairly sturdy cardboard trays with high sides (like you'd get in a stadium concession stand) and it was easy and light to keep one in my bag and helped in those instances.
The wristlet gift card is a great idea for convenience and budgeting. I would suggest you also have some cash with you as they sometimes have to shut down the electronics at the outdoor booths when lightning is in the area. Some booths have registers at both ends (Canada, Mexico, Japan come to mind) ... they're not always open but worth checking.
There will be a festival passport available at either entry to EPCOT (with the maps) and also in some shops. The passport will list by booth the various items available, and you can "check off" what you try as you go (you need to bring your own pen/pencil). The passport is also where you'd keep track of your progress in the fromage montage (in those instances the cast member at the booth will stamp your passport). There is also an unofficial app called WDW Food&Wine that also has the menus and lets you create a wish list that a lot of people use.
The Remy scavenger hunt (or Pluto's pumpkin pursuit) are both fun activities - you can do them yourself for free just by hunting for the items in each pavilion or you can purchase the map and redeem for a small prize. You can redeem without ever finding a single item -- they don't test you on it.
We typically don't do the concerts either, but you can hear the music from anywhere in the America pavilion so if a band you are interested in without wanting to invest time in the full concert you can plan to be in the same area for a show.
Sorry - that was probably more than you wanted.