Hi, Julie!
Your vacation is just days away! You have got to be excited :)
You can absolutely use Disney Gift Cards to pay for your meals at all three of these fantastic locations! Use your Disney Gift Card(s) as your method of payment when the bill is presented and you'll be good-to-go.
Gratuity is included for parties of six or more, but make sure you look at your receipt to confirm - Disney dining receipts will still include a line for "additional gratuity" even though It was already added, so make sure you double check; I might have learned this tip the hard way.
Another tip I'd like to share: if you are staying at a Walt Disney World® Resort hotel, for convenience, you can use your MagicBand to pay for your meals and purchases. Then, you can stop by the front desk of your Resort hotel to pay down your account with your Disney Gift Card(s). This way, you don't have to keep up with the cards while your enjoying the parks, and it is a great way of ensuring every penny on the gift card is maximized. I can't tell you the number of times I've come home from a magical vacation to find leftover gift cards with funds still available. I learned this trick the hard way, too.
If you won't be using a MagicBand, another option is to visit
Disneygiftcard.com. Guests are able to mange and consolidate their gift cards onto just one! This definitely makes things a bit more convenient. Select the highlighted link to check it out.
I hope this is useful, Julie! Please do not hesitate to reach out to me directly with any additional last-minute questions you may have.
Safe travels,
Faith